Covert cavitation: Spectral peak suppression in the acoustic emissions from spatially configured nucleations

Dual laser-nucleation is used to precisely configure two cavitation bubbles within a focused ultrasound field of f0 = 692 kHz, in proximity to the tip of a needle hydrophone. With both bubbles responding in the f0/2 sub-harmonic regime, confirmed via ultra-high speed shadowgraphic imaging, an emission spectrum with no sub-harmonic content is demonstrated, for an inter-bubble spacing ≈λ0. A spectral model for periodic shock waves from multiple nucleations demonstrates peak suppressions at nf0/2 when applied to the experiment, via a windowing effect in the frequency domain. Implications for single-element passive detection of cavitation are discussed

Stable-inertial cavitation

Research and development of applications utilising acoustic cavitation, particularly medical therapy, is often based on the spectrum of the scattered emissions collected during the cavitation occurrence. There is, however, limited understanding as to how driven bubble behaviour is related to the myriad of non-linear features that can exist within the cavitation noise spectrum, including those commonly reported. Moreover, there is an enduring tendency to classify cavitation activity as either stable or inertial, with no clear delineation between the two categories in terms of associated emissions. The work described in this thesis is dedicated to reconciling bubble dynamics driven by focused ultrasound, and resolved with ultra-high speed shadowgraphic imaging, to the acoustic emissions simultaneously detected via a broadband calibrated needle hydrophone system. Specifically, the role of periodic bubble collapse shock waves are experimentally investigated, supported by bubble oscillation models and spectral analysis. First, hydrophone-deconvolution for restoring an approximation to physical pressure data is demonstrated, through laser-plasma mediated bubble detection. Subsequent application to precision measurements of an acoustically driven cavitation bubble, verifies a contribution from periodic shock waves to all features within the emission spectrum, including the sub-harmonics. Moreover, complete spectral peak suppression at the sub-harmonic is demonstrated for a specific two-bubble configuration. Finally, the design of a bespoke passive cavitation detector, optimised for shock wave detection is described, and its performance evaluated against a comparable, commercially available device. Implications for cavitation detection and detector characterisation are discussed, as is the conventional classification of activity as stable or inertial, with reference to the literature

PI3K in T Cell Adhesion and Trafficking.

PI3K signalling is required for activation, differentiation, and trafficking of T cells. PI3Kδ, the dominant PI3K isoform in T cells, has been extensively characterised using PI3Kδ mutant mouse models and PI3K inhibitors. Furthermore, characterisation of patients with Activated PI3K Delta Syndrome (APDS) and mouse models with hyperactive PI3Kδ have shed light on how increased PI3Kδ activity affects T cell functions. An important function of PI3Kδ is that it acts downstream of TCR stimulation to activate the major T cell integrin, LFA-1, which controls transendothelial migration of T cells as well as their interaction with antigen-presenting cells. PI3Kδ also suppresses the cell surface expression of CD62L and CCR7 which controls the migration of T cells across high endothelial venules in the lymph nodes and S1PR1 which controls lymph node egress. Therefore, PI3Kδ can control both entry and exit of T cells from lymph nodes as well as the recruitment to and retention of T cells within inflamed tissues. This review will focus on the regulation of adhesion receptors by PI3Kδ and how this contributes to T cell trafficking and localisation. These findings are relevant for our understanding of how PI3Kδ inhibitors may affect T cell redistribution and function

Validity of the Keller-Miksis Equation for “non-stable” Cavitation and the Acoustic Emissions Generated

The Keller-Miksis equation (KME) is commonly used for numerical studies of inertial and stable-inertial cavitation. However, experimental validation of KME under clinically relevant exposure settings is scarce, particularly in terms of the acoustic emission signal generated by the cavitation. In this paper, the KME is validated against a cavitation cloud collapsing f0/2 and f0/3 sub-harmonically with some success. This could significantly aid the design of arrays for passive acoustic mapping (PAM), quantification of cavitation dose, and tuning controllers for feed-back-loops

Performance characterisation of a passive cavitation detector optimised for subharmonic periodic shock waves from acoustic cavitation in MHz and sub-MHz ultrasound

We describe the design, construction and characterisation of a broadband passive cavitation detector, with the specific aim of detecting low frequency components of periodic shock waves, with high sensitivity. A finite element model is used to guide selection of matching and backing layers for the shock wave passive cavitation detector (swPCD), and the performance is evaluated against a commercially available device. Validation of the model, and characterisation of the swPCD is achieved through experimental detection of laser-plasma bubble collapse shock waves. The final swPCD design is 20 dB more sensitive to the subharmonic component, from acoustic cavitation driven at 220 kHz, than the comparable commercial device. This work may be significant for monitoring cavitation in medical applications, where sensitive detection is critical, and higher frequencies are more readily absorbed by tissue

Medarbeiderundersøkelser - pliktløp, nyttig lederverktøy eller rasjonalisert myte? Et casestudie av medarbeiderundersøkelsen i Oslo kommune

Erfaringsbasert master 90 poengTema for denne avhandlingen er å utforske om medarbeiderundersøkelser som kartleggingsverktøy er et pliktløp, eller et nyttig verktøy for ledere. Det er tatt utgangspunkt i gjennomføringen av en slik undersøkelse i Oslo kommune. Det er undersøkt om kartleggingsmetoden bare er en pålagt plikt, om den gir en reell verdi og i hvilken grad resultatene kan brukes konstruktivt i utviklingen av arbeidsmiljøet. Avhandlingen er en induktiv studie, med en fenomenologisk tilnærming, og bygger på kvalitative intervjuer av ni ledere på ulikt nivå fra ulike virksomheter i Oslo kommune. Analysen har blant annet avdekket at instrumentelle betingelser kan bidra til å skape eierskap og forankring i organisasjonen, som videre skaper forpliktelser og engasjement for lederne til å arbeide med kartleggingsverktøyet. Medarbeiderundersøkelsen bidrar til å sette arbeidsmiljøet på dagsorden i virksomhetene, men lederne bestemmer i stor grad hvilke deler av resultatet som får oppmerksomhet. Det er i hovedsak resultater som kan brukes til å iverksette gruppeprosesser som står i fokus hos lederne. Kartleggingsverktøyet egner seg, i følge lederne, ikke til individuell oppfølging av enkeltansatte. Medarbeiderundersøkelsen gir lederne et inntrykk av arbeidsmiljøsituasjonen i virksomheten, og resultatet oppfattes som et "speilbilde" på hvor godt de fungerer som ledere. De føler også sterkt eierskap til resultatene, og dette skaper forpliktelse for oppfølgingsarbeidet. Avhandlingen viser at medarbeiderundersøkelsen ikke nødvendigvis er et pliktløp der praksisfeltet forblir uberørt. Medarbeiderundersøkelsen framstår i større grad som et nyttig verktøy for ledere til å iverksette konkrete forbedringstiltak. Det bærer likevel mer preg av å være et utpreget lederverktøy da det bidrar med nyttig informasjon som er av større interesse for lederne enn de ansatte. Dette gjenspeiler seg også ved at lederne i stor grad beslutter hvilke deler av resultatet som får oppmerksomhet.The theme of this thesis is to explore whether employee-surveys, as mapping methods, is to be considered as tours of duty, or as useful tools for the management. The thesis' starting point is the implementation of such an employee-survey in the municipality of Oslo. It is examined whether the mapping method is only to be regarded as an imposed duty, or whether it provides a real value, and the extent to which the results can be used constructively in the development of the working environment. The thesis is an inductive study with a phenomenological approach, based on qualitative interviews with nine leaders at different levels in various municipal enterprises. The analysis has revealed that instrumental conditions can help establishing ownership and grounding within the organization, which creates obligations and engagement for leaders to work with mapping methods. The employee-survey contributes to put the work environment on the agenda, but the leaders determine to a large extent which parts of the results that gets attention. It is mainly the parts of the results that can be used to implement group-processes, that are in focus among the leaders. According to the leaders, the mapping method is not suitable for following up individual employees. The employee-survey gives leaders an idea of the work environment situation, and the result is perceived as a "reflection" on how well they function as leaders. They also feel a strong ownership towards the results, and this creates commitment for follow-up work. The thesis shows that the employee-survey is not necessarily regarded as a tour of duty where the practice field remains untouched. The employee survey emerges more as a useful tool for leaders to implement specific improvement measures. Still, it carries more signs of being a distinct management-tool, as it provides useful information that is of greater interest to the leaders than to the employees. This is also reflected by the fact that the leaders, to a large extent, decide which parts of the employee-survey results gets the attention

Rationale and design of the Birkebeiner Ageing Study – a prospective cohort study of older endurance athletes

Background - While regular physical activity is associated with reduced mortality and morbidity in general populations, health outcomes and functional capacity related to upholding strenuous endurance exercise beyond the age of 65 years are only sparsely studied. The aim of this study is to assess associations of prolonged strenuous endurance sport practice with ageing, functional decline, morbidity and longevity among older recreational endurance athletes, during long-term follow-up. Methods - Prospective cohort study of older recreational endurance athletes in Norway. All skiers aged 65 years and older who participated in a long-distance endurance competition, the annual 54-km Birkebeiner cross-country ski race in 2009 or 2010, were invited. The participants answered an extensive baseline questionnaire about lifestyle habits, including leisure-time physical activity and endurance sport participation, diseases, medication use and physical and mental health, with follow-up questionnaires planned every fifth year until 2029. New participants may be invited with the aim to increase the study size. Endpoints such as all-cause and disease-specific mortality, incidence and cumulative prevalence of diseases, use of medication, physical and mental health and functional decline will be assessed subsequently. Out of 658 invited skiers (51 women), 551(84%) completed the baseline questionnaire and were included in the study. The mean age was 68.8 years (median 68, range 65- 90). At baseline, the participants had completed the Birkebeiner race for an average of 16.6 years and reported an average of 33.4 years of regular endurance exercise, with one out of five reporting at least 50 years of exercise. In all, 479 (90%) reported that they were still practicing leisure-time physical activity of moderate or vigorous intensity at least twice weekly. The prevalence of cardiovascular risk factors and diseases was low. Discussion - This prospective study of a cohort of recreational athletes exposed to prolonged and strenuous endurance exercise, could complement population-based studies by providing data on associations between life-long endurance sport participation, aging, functional decline and health outcomes during long-term follow-up

Bevara eller riva? - Ein studie av historiebruk i to byggjesaker i Stavanger og Sandnes, 2012-2019

Samandrag Denne masteroppgåva i historie tar del i fleire fagfelt innanfor historiefaget, sjølv om det må poengterast at nokre av fagfelta er tverrfaglege i sin natur. Blant anna fagfelta historiebruk, bygningsvern, og byutvikling vert utforska. Problemstillinga i oppgåva lyd som følgande: Kva slags historie vert nytta av dei ulike partane i ei lokalpolitisk sak om riving eller bevaring av eit bygg? Og kan ein seia noko om korleis denne bruken av historie påverka utfallet av saka? For å utforska denne problemstillinga har eg gjort ein historisk tekstanalyse av alle politiske dokument som omhandlar byggjesakene 12/5770 om Kirkegata 22 i Stavanger, og 19/07885 om Havnegata 4 i Sandnes, og alle mediekjeldene eg kunne finna som omhandlar byggjesakene. Her har eg forsøkt å finna og tolka alt som går under historiebruk og bruk av historie. I konklusjonen til oppgåva argumenterer eg for å ha avdekt ein forskjell i korleis partane som ville bevara og partane som ville riva eit bygg nytta historie i sine argument i to lokale byggjesaker i Stavanger og Sandnes. Dei som ville bevara bygg fokuserte mest på fortida og korleis ein må ta vare på den i dag, mens dei som ville riva fokuserte mest på framtida og vidare utvikling av byen. Kanskje kan dette også vera ein del av svaret på kvifor begge byggjesakene enda med riving, og dermed nederlag for dei som ville bevara bygga. Dette er iallfall eit spennande spørsmål som ein treng meir forsking på.Abstract This Master thesis in the subject of history takes part in many fields of the subject, though it must be said that some of these fields are naturally interdisciplinary. Among the fields explored are historical use, building conservation and urban development. The thesis statement is as follows: What type of history is used by the participants in a local political case about demolition or conservation of a building? And can this be used to say something about how the use of history affected the results of the political cases? To explore this thesis further, I did a historical text analysis of all the political documents regarding building case 12/5770 about Kirkegata 22 in Stavanger, and case 19/07885 about Havnegata 4 in Sandnes, and all the documents from the media that regards said building cases. I have in this work tried to find and interpret everything that can be called use of history. In the conclusion of my thesis, I argue that I have shown a difference in the ways history is used by the participants in a local political debate regarding demolition or conservation of a building. The difference is that participants who wish to conserve the building, mostly focus on the city’s and building’s past, and how to preserve it and its history in the future, while participants wanting to demolish the building focus more on the future and the further development of the city. Can this also be a part of the reason why the political cases ended as they did, with demolition of the buildings and defeat for those in favor of conservation? One thing is certain: this is an interesting subject with opportunities for a lot more research

Recombinant snakebite antivenoms: A cost-competitive solution to a neglected tropical disease?

Snakebite envenoming is a major public health burden in tropical parts of the developing world. In sub-Saharan Africa, neglect has led to a scarcity of antivenoms threatening the lives and limbs of snakebite victims. Technological advances within antivenom are warranted, but should be evaluated not only on their possible therapeutic impact, but also on their cost-competitiveness. Recombinant antivenoms based on oligoclonal mixtures of human IgG antibodies produced by CHO cell cultivation may be the key to obtaining better snakebite envenoming therapies. Based on industry data, the cost of treatment for a snakebite envenoming with a recombinant antivenom is estimated to be in the range USD 60-250 for the Final Drug Product. One of the effective antivenoms (SAIMR Snake Polyvalent Antivenom from the South African Vaccine Producers) currently on the market has been reported to have a wholesale price of USD 640 per treatment for an average snakebite. Recombinant antivenoms may therefore in the future be a cost-competitive alternative to existing serum-based antivenoms