Volcanic Activity: Processing of Observation and Remote Sensing Data (VAPOR)

The World Bank makes a very clear distinction between disasters and natural phenomena. Natural phenomena are events like volcanic eruptions. A disaster only occurs when the ability of the community to cope with natural phenomenon has been surpassed, causing widespread human, material, economic or environmental losses. By these definitions, volcanic eruptions do not have to lead to disasters. On November 13, 1985, the second most deadly eruption of the twentieth century occurred in Colombia. Within a few hours of the eruption of the Nevado del Ruiz volcano, 23,000 people were dead because no infrastructure existed to respond to such an emergency. Six years later, the 1991 eruption of Mount Pinatubo in the Philippines was the largest volcanic eruption in the 21st century to affect a heavily populated area. Because the volcano was monitored, early warning of the eruption was provided and thousands of lives were saved. Despite these improvements, some communities still face danger from volcanic events and volcano-monitoring systems still require further development. There remain clear gaps in monitoring technologies, in data sharing, and in early warning and hazard tracking systems. A global volcano-monitoring framework such as the VIDA framework can contribute to filling these gaps. VIDA stands for “VAPOR Integrated Data-sharing and Analysis” and is also the Catalan and Spanish word for ‘life’. The ultimate goal for this project is to help save the lives of people threatened by volcanic hazards, while protecting infrastructure and contributing to decision support mechanisms in disaster risk management scenarios

Arterial Tissue Perforation Using Ultrasonically Vibrating Wire Waveguides

Chronic Total Occlusions (CTOs) are fibrous and calcified atherosclerotic lesions which completely occlude the artery. They are difficult to treat with standard dilation procedures as they cannot be traversed easily. Their treatment is also associated with a high risk of arterial perforation. Low frequency ultrasonic vibrations delivered via wire waveguides represent a minimally invasive treatment for CTOs and other tissue ablation applications. These devices typically operate at 20–50 kHz delivering wire waveguide distal tip amplitudes of vibration of 0-60 μm. The diseased tissue is ablated or disrupted by repetitive direct mechanical contact and cavitation. This research assesses the susceptibility of arterial tissue to perforation and residual damage under the action of ultrasonically energised wire waveguides. Using Finite Element Analysis (FEA), a linear acoustic model of the wire waveguide distal tips can predict the pressures for a range of operating parameters typically used for these devices. High mesh densities (140 EPW) were required to solve the entire acoustic field, including complex wave interactions. The FEA model was used to aid in the further design and modification of an ultrasonic apparatus and wire waveguide (0–34.3 μm at 22.5 kHz). Using a test rig, the effects of distal tip amplitudes of vibration, feedrate and angled entry on the perforation forces, energy and temperature were measured. The perforation forces reduced (≈ 60%, 6.13 N - 2.46 N mean) when the wire waveguide was energised at low amplitudes of vibrations (\u3c 27.8 μm). There were no significant change in tissue perforation forces above this or when the waveguide was operating above the cavitation threshold. Histological analysis also showed tissue removal. While this knowledge is useful in the prediction and avoidance of perforations during CTO operations; it is also envisaged that this information can aid in the design and development of generic ultrasonic wire waveguide tissue cutting tools

An investigation into cold weld adhesion for spacecraft repair after a space debris impact using space education based sub-orbital sounding rocket platform

It has been observed that similar metallic materials, when in contact and undergoing relative displacements, can fuse or weld. In standard atmospheric conditions it is not common but in the space environment the inability of the surface interfaces to re-oxide after abrasive contact is hindered, atomic diffusion of the metal occurs, and this can lead to fusion. Oscillatory motion and Hertzian contact stress between the two surfaces plays a major role in the strength of the cold welded joint. It has been shown that the action of a low fretting load can almost double the adhesion force under cyclic loading even in terrestrial atmospheric conditions. In space, cold welding was first identified in the 1960’s as an adverse reaction. It has been attributed to anomalies and failures of deployable mechanisms. Other research has alluded to the potential of this phenomena for use in spacecraft repair in space. Examples where this may hold promise is repair of a spacecraft hull breach after hypervelocity impacts due to micrometeoroids or orbital debris. This research proposes an investigation into cold welding for use in spacecraft hull repair. The research intends to qualify an experimental apparatus to TRL 4 using a sub-orbital sounding rocket platform. A joint research effort between the Aerospace, Mechanical and Electronic Department at I.T. Carlow, Ireland, the Department of Aviation at Malta College of Arts, Science, and Technology, Malta is underway. The project aims at developing a test apparatus to apply a number of custom patches to simulated hypervelocity spacecraft hull breaches and investigate the adhesion properties during re-entry for a range of mechanical application conditions. A number of chambers may be tested and monitored using pressure transducers. After Phase 1 (terrestrial development and validation using a vacuum chamber), there will be an application to education based space programmes such as the one offered by the European Space Agency (REXUS). The core of the activity will be the design and testing of the experimental payload, simulating hull breaches, deployment the repair patch and monitoring of its performance during re-entry (Phase 2). The recovery of the payload will allow further metallurgical analysis of the cold welded joint (Phase 3). A conceptual 3-D model of the payload has been developed and is presented here. The data acquired from the sub-orbital flight experiment will test the validity of the hypothesis for use of cold welding for spacecraft hull repair but will also detail the development and implementation of mock hypervelocity impacts to rocket skin for the purposes of simulating hull breaches in the space environmen

Soft Tissue Cutting with Ultrasonic Mechanical Waveguides

The use of ultrasonic vibrations transmitted via small diameter wire waveguides represents a technology that has potential for minimally invasive procedures in surgery. This form of energy delivery results in distal tip mechanical vibrations with amplitudes of vibration of up to 50 μm and at frequencies between 20-50 kHz commonly reported. This energy can then be used by micro-cutting surgical tools and end effectors for a range of applications such as bone cutting, cement removal in joint revision surgery and soft tissue cutting. One particular application which has gained regulatory approval in recent years is in the area of cardiovascular surgery in the removal of calcified atherosclerotic plaques and chronic total occlusions. This paper builds on previous work that was focused on the ultrasonic perforation of soft vascular tissue using ultrasonically activated mechanical waveguides and the applied force required to initiate failure in soft tissue when compared with non-ultrasonic waveguides. An ultrasonic device and experimental rig was developed that can deliver ultrasonic vibrations to the distal tip of 1.0 mm diameter nickel-titanium waveguides. The operation of the ultrasonic device has been characterized at 22.5 kHz with achievable amplitudes of vibration in the range of 16 – 40μm. The experimental rig allows the ultrasonically activated waveguide to be advanced through a tissue sample over a range of feedrates and the waveguide-tissue interaction force can be measured during perforation into the tissue. Preliminary studies into the effects of feedrate on porcine aortic arterial tissue perforation forces are presented as part of this work. A range of amplitudes of vibration at the wire waveguide distal tip were examined. The resulting temperature increase when perforating artery wall when using the energized wire waveguides is also examined. Results show a clear multistage failure of the tissue. The first stage involves a rise in force up to some critical force and tissue displacement whereby the cut is initiated. The results show that with increasing ultrasonic amplitude of vibration the perforation force decreases considerably. The current results show that for the range of feedrates investigated 19-95 mm/min at an amplitude of vibration of 34.3 μm there was no significant effect on the perforation initiation force. The ΔT in the tissue 3.0 mm from the point of entry is also presented for a range of amplitudes of vibration

Ultrasonic Angioplasty: Assessing the Risk of Arterial Perforation

Atherosclerosis is a cardiovascular disease that effects large and medium muscular arteries (such as coronary and iliac) and also large elastic arteries (such as aorta) [1]. It causes thickening of the arterial wall and over time can result in a completely blocked artery or chronic total occlusion (CTO). While the majority of atherosclerotic lesions can be attempted by typical Percutaneous Transluminal Coronary Angioplasty (PTCA) such as balloon and stent implantation, calcified CTOs are often problematic as they do not lend themselves to be accessed by the guidewire which is required to implant the balloon and stent. Excessive guidewire pushing force may result in arterial perforation with CTOs often requiring invasive by-pass surgery. An alternative method proposes the use of low frequency high power ultrasound transmitted through wire waveguides for the removal of the calcified material from advanced atherosclerotic lesions. This type of energy manifests itself as a mechanical vibration at the distal tip of the wave guide with amplitudes of up to 100 microns and frequencies ranging between 20-45 kHz commonly reported. The ultrasound acts to disrupt calcified diseased tissue by means of direct contact ablation, cavitation, acoustic steaming and other pressure wave components while the elastic tissue remains largely unaffected [2]. In this study the effects of this form of ultrasound on healthy arterial tissue (porcine aorta) is examined. Experiments were carried out to determine the force required to perforate healthy porcine arterial tissue both with and without ultrasound at various distal tip displacements

Ablation of Chronic Total Occlusions Using Kilohertz-Frequency Mechanical Vibrations in Minimally Invasive Angioplasty Procedures.

Certain minimally invasive cardiology procedures, such as balloon angioplasty and stent implantation, critically require that the site of an arterial blockage be crossed by an intraluminal guidewire. Plaques resulting in near or totally occluded arteries are known as chronic total occlusions (CTOs), and crossing them with conventional guidewires is a significant challenge. Among the most promising proposed solutions is the delivery of high power, low frequency ultrasonic vibrations to the occlusion site via an intraluminal wire waveguide. The vibrating distal-tip of the ultrasound wire waveguide is used to transmit energy to the surrounding plaques, tissues and fluids in order to ablate or weaken atherosclerotic plaque. Potential mechanisms of interaction with the plaque and adjacent fluids identified in the literature include; (i) direct contact with the waveguide distal tip, (ii) subcavitational acoustic fluid pressure fluctuations, (iii) cavitation, and (iv) acoustic streaming. This article will summarize developments in this area over more than two decades, describing experimental methods for device performance characterization, preclinical tests, early clinical investigations and, later, full clinical trials. The article will also review theoretical foundations, and numerical models suitable for device design and analysis. Finally, important issues for future research and for the development of this technology will be considered

Increased Susceptibility of Arterial Tissue to Wire Perforation with the Application of High Frequency Mechanical Vibrations

High frequency mechanical vibrations (20–50 kHz), delivered via small diameter flexible wire waveguides represent a minimally invasive technology for the treatment of chronic total occlusions (CTOs) and in other tissue ablation applications. Tissue disruption is reported to be caused by repetitive mechanical contact and cavitation. This work focuses on the effects of vibrating wire waveguides in contact with arterial tissue. An apparatus with clinically relevant parameters was used, characterized as operating at 22.5 kHz and delivering amplitudes of vibration of 17.8 - 34.3 µm (acoustic intensity, ISATA: 1.03 - 3.83 W/cm2) via 1.0 mm diameter waveguides. Inertial cavitation (in water at 370C) was determined to occur above amplitudes of vibration greater than 31.4 µm (ISATA = 3.21 W/cm2). The energized waveguides were advanced through tissue samples (porcine aorta) and the force profiles were measured for a range of acoustic intensities. The results show that the tissue perforation initiation force, perforation initiation energy and total energy required to perforate the tissue reduces with increasing acoustic intensity. No significant reduction in perforation force or energy was observed in the inertial cavitation region. Multistage perforation was evident through the force profile and histological examination of the tissue samples post wire waveguide perforation

Perforation of Arterial Tissue Using Kilohertz Frequency Ultrasound Delivered via Wire Waveguides

An emerging technology proposes the use of low frequency-high power ultrasound transmitted via wire waveguides for the disruption and ablation of atherosclerotic lesions, more specifically advanced fibrous or calcified plaques such as chronic total occlusions (CTO). This energy delivery selectively ablates rigid diseased tissue by means of direct mechanical contact, cavitation and other forces generated by the intense dynamic pressure fields generated. The first clinical device using this energy delivery was granted FDA approval in 2007 [1] for the ablation of CTOs and most research to date has focused on ablation and disruption of hard, fibrous or calcified tissues [2]. This work, however, investigates the affects this energy delivery has on the perforation of soft healthy tissue (porcine aorta). Materials and methods An ultrasonic apparatus has been developed with operational characteristics similar to clinical devices reported in the literature i.e. frequency of operation (22.5kHz) and distal-tip ultrasonic amplitudes of vibration (~15-50μm). This apparatus delivers ultrasound via 1mm nitinol wire waveguides (132mm in length) with flat distal tips. An experimental test rig was developed to perform controlled tests (ultrasonic power delivery and feedrates) on tissue samples in a thermostatic tank (37oC). Perforation force measurement was achieved by means of a strain gauge arrangement on a cantilever tissue holder. A miniature hydrophone was also incorporated for the detection of cavitation by analysing the acoustic spectrum while the device was activated. Sub, super and ultra harmonics of the fundamental are all considered indicative of stable cavitation, whereas an increase in the broadband noise, in regions absent of significant harmonics, are indicative of inertial cavitation [3]. Porcine aorta was exhumed, stored in saline and tested less then 24 hours after death. Connective tissue was removed and samples (10x20mm) were cut from the descending aorta. Wires were advanced towards the tissue at a constant feedrate of 38 mm/min until perforation. Results As shown in Figure 1, an increase in distal tip amplitudes of vibration reduced the perforation force. It was found that stable cavitation occurred at all power settings (\u3e 15μm). At the high power displacement amplitude setting of 34.3μm the perforation force was 1.2N when compared with 5.5N with no ultrasonic activation. The inertial cavitation threshold was crossed at distal-tip amplitudes of vibration greater than 30μm. However, no significant decrease in perforation force was evident in the inertial cavitation region. At the macro level, the tissue appears to fail in a similar manner for all distal-tip amplitudes of vibration. Discussion Perforation force of soft arterial tissue does not appear to be significantly effected by the onset of inertial cavitation. Further histological examination may be required to determine residual tissue damage from cavitation. Additional studies are needed to determine to what extent tissue is ablated, cut or removed at various power levels. It is suggested, however, that tissue removal using this energy on soft tissue is minimal when compared to that of hard brittle tissue ablation

Urocortin 3 marks mature human primary and embryonic stem cell-derived pancreatic alpha and beta cells.

The peptide hormone Urocortin 3 (Ucn 3) is abundantly and exclusively expressed in mouse pancreatic beta cells where it regulates insulin secretion. Here we demonstrate that Ucn 3 first appears at embryonic day (E) 17.5 and, from approximately postnatal day (p) 7 and onwards throughout adult life, becomes a unifying and exclusive feature of mouse beta cells. These observations identify Ucn 3 as a potential beta cell maturation marker. To determine whether Ucn 3 is similarly restricted to beta cells in humans, we conducted comprehensive immunohistochemistry and gene expression experiments on macaque and human pancreas and sorted primary human islet cells. This revealed that Ucn 3 is not restricted to the beta cell lineage in primates, but is also expressed in alpha cells. To substantiate these findings, we analyzed human embryonic stem cell (hESC)-derived pancreatic endoderm that differentiates into mature endocrine cells upon engraftment in mice. Ucn 3 expression in hESC-derived grafts increased robustly upon differentiation into mature endocrine cells and localized to both alpha and beta cells. Collectively, these observations confirm that Ucn 3 is expressed in adult beta cells in both mouse and human and appears late in beta cell differentiation. Expression of Pdx1, Nkx6.1 and PC1/3 in hESC-derived Ucn 3(+) beta cells supports this. However, the expression of Ucn 3 in primary and hESC-derived alpha cells demonstrates that human Ucn 3 is not exclusive to the beta cell lineage but is a general marker for both the alpha and beta cell lineages. Ucn 3(+) hESC-derived alpha cells do not express Nkx6.1, Pdx1 or PC1/3 in agreement with the presence of a separate population of Ucn 3(+) alpha cells. Our study highlights important species differences in Ucn 3 expression, which have implications for its utility as a marker to identify mature beta cells in (re)programming strategies

Examining the effect of challenge and threat states on endurance exercise capabilities

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordThis paper presents the first two studies to explore the effect of challenge and threat states on endurance exercise capabilities. In study one, relationships between cardiovascular markers of challenge and threat states, ratings of perceived exertion (RPE), and exercise tolerance were explored during moderate- and severe-intensity cycling. Cardiovascular reactivity more reflective of a challenge state (i.e., relatively higher cardiac output and/or lower total peripheral resistance reactivity) predicted lower RPE throughout moderate- but not severe-intensity cycling. Building on these findings, study two experimentally manipulated participants into challenge, threat, and neutral groups, and compared 16.1 km time-trial performances, where pacing is self-regulated by RPE. Participants completed familiarisation, control, and experimental visits while physiological (oxygen uptake), perceptual (RPE), and performance-based (time to completion [TTC] and power output [PO]) variables were assessed. When compared to the threat group, the challenge group demonstrated cardiovascular responses more indicative of a challenge state, and delivered faster early-race pacing (PO) at similar RPE. Although there were no significant differences in TTC, results revealed that augmentations in PO for the challenge group were facilitated by tempered perceptions of fatigue. The findings suggest that an individual's pre-exercise psychophysiological state might influence perceived exertion and endurance exercise capabilities