Controlling and predicting rupture and dewetting of quiescent thin water films, hundreds of microns thick, was studied experimentally. Wax, polycarbonate, steel and aluminium surfaces were immersed in water; the water level was lowered to form thin films above the surfaces. Spontaneous film rupture only occurred on wax, a low-energy surface. Films ruptured at the edges of the other—high-energy—surfaces. Increased surface roughness decreased chances of rupture and dewetting in the film. Introducing large wax or steel protrusions (on the order of millimetres) on smooth surfaces showed films rupturing above the protrusions and adhering to them; further thinning caused rupture and dewetting away from the protrusions. Entrapped air bubbles, injected through the surface and into the film, ruptured as they breached the film surface to form stable holes in the film if it was sufficiently thin. Entrapped air was the best means of rupturing films on all surfaces.

Orientador: Winston Bonetti Yoshida / Resumo: A Síndrome do Aprisionamento da Artéria Poplítea (SAAP) é uma doença caracterizada pela compressão extrínseca dessa artéria, causada pelo desvio de seu trajeto anatômico habitual ou por estruturas músculo-tendinosas da fossa poplítea. Os sintomas clínicos costumam aparecer quando os indivíduos realizam esforços físicos. Distinguem-se dois tipos de SAAP: a clássica ou congênita e a funcional ou adquirida. Na forma clássica, distúrbios do desenvolvimento embrionário provocam anomalias da artéria poplítea ou de estruturas adjacentes que ocasionam a compressão. Na forma funcional ou adquirida, identifica-se apenas hipertrofia dos músculos gastrocnêmios como possível causa do encarceramento. O diagnóstico, em ambos os tipos, é feito pela detecção de oclusão ou estenose significativa da artéria poplítea às manobras de dorsiflexão e hiperextensão ativa dos pés, utilizando-se o mapeamento dúplex, a ressonância magnética ou a arteriografia. A identificação desses testes positivos em indivíduos assintomáticos e sem alterações anatômicas, trouxe questionamentos a respeito da especificidade dos testes diagnósticos. Neste trabalho é feita uma revisão da SAAP anatômica e funcional, além de serem discutidas a acurácia, sensibilidade e especificidade dos testes diagnósticos em cada caso. / Abstract: The popliteal artery entrapment syndrome (PAES) is characterized by extrinsic compression of this artery as a result of anatomic deviation from its usual course, or by compression from musculotendinous structures in the popliteal fossa. Clinical symptoms onset when these affect individuals are undergoing stressing exercise. There are two types of PAES: classical or congenital form, and a functional acquired form. In the classical form, disturbances in the embryogenesis lead either directly to popliteal artery anomalies or to alterations of adjacent structures which cause compression of the popliteal artery. In the functional form, hypertrophy of the gastrocnemius muscle secondary to exercise has been postulated as a cause. In both types, diagnosis is made in subjects, on finding total occlusion or important stenosis of the popliteal artery. This is identified by duplex scan, magnetic resonance or arteriography during active plantar flexion-extension. A positive test in non-symptomatic subjects presenting no anatomical anomalies led to discussion regarding its sensibility and specificity. A review of anatomical and functional PAES besides a discussion about accuracy, sensibility and specificity of those diagnostics tests was made in this study. / Mestre

Abstract Bone marrow mesenchymal stromal cells (MSCs) and mononuclear cells (BM-MNCs) have shown great therapeutic potential in various clinical settings. Although intravascular transplantation of the cells constitutes the optimal delivery route, massive pulmonary entrapment, with the threat of embolization, remains a major obstacle for using this type of therapy. Because pulmonary entrapment is at least partially mediated by adhesion molecules, cell surface modification could enhance pulmonary passage. We used a porcine model of allogeneic MSC and autologous BM-MNC transplantation and radionuclide labelling to track the cells. The role of the transplantation route on lung entrapment, biodistribution, safety and BM-MNC targeting to the injured brain was studied. Effects of pronase detachment on the lung passage of MSCs were studied in porcine and murine models; a rat model of acute limb injury was used to further evaluate tissue targeting. Treatment with pronase to detach cell surface molecules and the effect on stem cell potential was assessed in vitro. Intra-arterial administration of MSCs diminishes their lung deposition; intravascular transplantation did not cause pulmonary embolisms. Intra-arterially transplanted BM-MNCs did not reach the brain in significant numbers. Transient proteolytic modification of MSCs with pronase decreased lung accumulation and tissue targeting without affecting their therapeutic characteristics. Intra-arterial transplantation increases lung passage of MSCs. Although thromboembolic events were not observed, further studies are warranted to ensure the safety of this route of MSC delivery. Pronase detachment is a promising method to enhance the potential of systemic MSC therapies. / Tiivistelmä Luutytimen mesenkymaaliset kantasolut (MSC) ja mononukleaariset solut (BM-MNC) ovat osoittautuneet tehokkaiksi useissa kliinisissä käyttöaiheissa. Solujen systeeminen annostelu verenkiertoon olisi käytännön kannalta paras soluterapian toteutukseen, mutta solujen merkittävä taipumus jäädä keuhkoihin loukkuun ja veritulppariski muodostavat haasteen. Keuhkohakeutumisen tiedetään ainakin osin johtuvan solujen pintamolekyyleistä ja näiden muokkaaminen voisi parantaa solujen keuhkoläpäisevyyttä. Tutkimuksessa käytettiin koe-eläimenä sikaa, jolle istutettiin systeemisesti allogeenisia mesenkymaalisia kantasoluja tai autologisia luuytimen mononukleaarisia soluja; solujen kudoshakeutumisen seuranta toteutettiin isotooppileimauksella- ja kuvannuksella. Tutkimuksessa arvioitiin annostelureitin vaikutusta keuhkoläpäisevyyteen, solujen kudojakautumista, toimenpiteen turvallisuutta sekä mononukleaarisolujen hakeutumista vaurioituneeseen aivokudokseen. Pronaasikäsittelyn vaikutusta mesenkymaalisten kantasolujen keuhkoläpäisevyyteen arvioitiin sika- ja hiirimallissa; rotan raajavauriomallia käytettiin lisäksi pronaasin kudoshakeutumisvaikutusten arvioimiseen. Pronaasikäsittelyn vaikutuksia solujen pintarakenteisiin ja toiminnallisuuteen arvioitiin in vitro- kokeissa. Mesenkyymalisten kantasolujen annostelu valtimonsisäisesti paransi solujen keuhkoläpäisevyyttä; tutkimuksissa käytetyt solut eivät aiheuttaneet keuhkoveritulppia. Valtimonsisäisesti annostellut mononukleaarisolut eivät hakeutuneet vaurioituneeseen aivokudokseen sikamallissa. Pronaasikäsittely muovasi solujen pintaproteiineja palautuvasti ja tämä lisäsi huomattavasti mesenkymaalisten kantasolujen keuhkoläpäisevyyttä ja kudoshakeutumista vaikuttamatta solujen toiminnallisuuteen. Mesenkymaalisten kantasolujen annostelu valtimonsisäisesti voi parantaa solujen keuhkoläpäisevyyttä. Tutkimuksessa ei todettu keuhkoveritulppaa tai muita tromboembolisia tapahtumia, mutta lisätutkimuksia tarvitaan MSC- terapian turvallisuuden takaamiseksi. Pronaasikäsittelyn tulokset mesenkymaalisten kantasolujen systeemisen annostelun parantamisessa olivat lupaavia.

This thesis investigated the longitudinal role of defeat and entrapment in populations where these factors were expected to be particularly relevant (a sample of individuals from areas of socioeconomic deprivation and a sample of formal caregivers). The thesis then considered whether defeat and entrapment influenced reward sensitivity on a gambling task and lastly, designed a short scale measuring defeat and entrapment suitable for use in clinical populations. The research incorporated a review of the literature, two longitudinal studies, a behavioural study and the development of a scale. The literature review presented in Chapter 1 provided evidence of a well-established link between defeat, entrapment and poor mental health, suggesting that defeat and entrapment may act as a transdiagnostic process; contributing to the development and maintenance of a range of mental disorders. However, the review also demonstrated that defeat and entrapment relate to the same experiences, suggesting that logically these constructs may equally co-occur, although the structure of the constructs is currently debated. The studies presented in Chapters 3 and 4 demonstrated that perceptions of defeat and entrapment predicted poor mental health (depression and anxiety, and depression and caregiver burden) at a second time point, 12 months later. These chapters presented the first longitudinal evidence for samples recruited from the general population and occupational settings. Furthermore, these chapters provided evidence that the relationship between defeat, entrapment and poor mental health operates in a bidirectional way within a sample recruited from community settings, but a linear way within a sample of formal caregivers, suggesting that further research is needed to confirm the direction of this relationship. The research presented in Chapter 5 found a non-significant relationship between defeat and entrapment and reward sensitivity among a sample of undergraduate students. This may have arisen due to the generally low levels of defeat and entrapment within the sample despite highly varied performance on the task. Replication of this research within a sample where a wider range of defeat and entrapment experiences would be expected might be beneficial. Additionally, this thesis aimed to confirm the factor structure of defeat and entrapment amongst various populations. Exploratory and confirmatory factor analysis demonstrated that defeat and entrapment are best conceptualised as a single psychological construct (Chapters 3 and 6), supporting one-factor theories of defeat and entrapment (e.g. Taylor et al., 2011a). During the course of conducting research for this thesis, it became apparent that the length of existing scales used to measure defeat and entrapment were not suitable for use with clinical populations. Despite evidence that defeat and entrapment may reduce symptoms of mental health problems, their measurement has not yet translated to clinical practice. Although several reasons underlie this, a lack of short measurement tool is a major factor. To address this, an eight-item scale was developed, which demonstrated good psychometric properties across four samples from clinical and non-clinical settings. The current research was supported by a discussion of the clinical implications of the work, specifically identifying how defeat and entrapment could be implemented within therapeutic interventions for mental health problems. The current thesis represents a significant contribution to original research considering defeat and entrapment as predictors of mental health problems. The thesis presents the first longitudinal evidence that defeat and entrapment impact on mental health problems for individuals recruited from community and occupational settings and first application of defeat and entrapment to a behavioural task. Through development of a short scale, the thesis also presents a potential avenue to increase the measurement of defeat and entrapment in clinical settings.

No description available.

In 1996 the state of Nepal was challenged by a Maoist insurgency, resulting in a decade-long civil war. During the course of the subsequent peace process the parliamentary parties found themselves agreeing to significant political changes, including a republican constitution. This study approaches the Nepal case on the assumption that the discursive aspect of social relations is one important factor in understanding how specific events unfold and why actors do one thing and not another. Two frames are investigated using frame analysis in terms of their representation of problem, cause and solution: a terrorism frame from the period of conflict and a peace frame from the period of conflict resolution. The terrorism frame is categorised as a negative frame and the peace frame as a positive frame. This overarching difference is found to have implications for the effects of the respective frames. In contrast to traditional frame analysis, which tends to focus on the success of a frame and the effects on a specific audience, this study investigates the effects of frames on the actors involved in the framing process in terms of their perceived manoeuvrability for action. This approach is formalised in a model of four types of logic of actor effects that is applied to the Nepal case. The analysis of frame effects is based on first-hand interviews with key actors, such as former prime ministers and top leaders of political parties and civil society. From this material, the study gives insight into how the two frames influenced the actors’ perceived manoeuvrability. This actor-centred approach shows that the frames affected the actors in both enabling and restrictive ways and thus influenced the outcome in Nepal. For example, it is shown that frames created during the conflict were considered a prerequisite for the legitimate use of military force. The study also shows the unintended effects of framing, captured in the model as the effect of self-entrapment, and highlights the coercive character of ideas in making actors perceive themselves as forced to take a certain action or position.

Text in Afrikaans / Alhoewel die lokvalstelsel as misdaadbekampingsmetode lank reeds bestaan, is die toepassing daarvan nog altyd kontroversieE!I. Hierdie omstredenheid is die laaste paar jaar op die voorgrond gedryf deur 'n Regskommissie-ondersoek, sowel as deur die aanvaarding van 'n Handves van Menseregte. Ondersoek word ingestel na hierdie omstredenheid deur te kyk na die inhoud en toepassing van die stelsel, sowel as na die rol wat private persona, die polisie en die hot by die stelsel speeL Die gevolgtrekking waartoe gekom word, is dat die omstredenheid van die stelsel te danke is aan die feit dat dit verband hou met pro-aktiewe regshandhawing, wat in wese bestaan uit die gebruik van misleiding ten einde die pleging van 'n misdaad teweeg te bring. Die probleem met pro-aktiewe regshandhawing is dat dit 'n geleentheid skep vir die uitoefening van polisiediskresie wat grootliks sonder beheer geskied, met potensiele wanoptrede aan die kant van regshandhawers en die ondermyning van die publiek se vertroue in die billikheid van die strafregspleging. Ondersoek word gevolglik ingestel na metodes om diskresie-uitoefening by die lokvalstelsel te regverdig, aangesien daar wei ruimte is vir diskresionere magte wat behoorlik begrens, gestruktureer en gekontroleer is. Die vernaamste metodes van beheer oor diskresie­ uitoefening by die lokvalstelsel, naamlik die uitsluiting van getuienis en weerstand in 'n strafgeding, word grondig ondersoek met verwysing na die Engelse-, Amerikaanse- en Kanadese reg. Dit is egter die uitgangspunt van hierdie proefskrif dat wetgewende strukturering van diskresie-uitoefening by die lokvalstelsel die mees effektiewe oplossing bied vir meeste van die problema van die stelsel. Die enigste aanvaarbare basis waarop die lokvalstelsel kan funksioneer, is om deur middel van wetgewing die trefwydte van toelaatbare lokvaltegnieke en die beperkinge waarbinne regshandhawers regsonderdane mag beweeg om misdade te pleeg, te definieer. Daar is dus 'n behoefte aan die kodifisering van standaarde waaraan voldoen moet word voordat enige lokvaloperasie behoort te begin. / Although the system of trapping has long been used as a method of preventing crime, its employment has always been controversial. In the recent past, this controversy has come to the front due to an investigation by the South African Law Commission and the acceptance of a Bill of Rights. This thesis investigates this controversy by looking at the contents and application of the system, as well as the role which private persons, the police and the court play in the system. The conclusion arrived at, is that the controversy surrounding the system is due to the fact that it has to do with pro-active law enforcement, which consists of the use of deception to induce the performance of a criminal act. The problem with pro-active law enforcement is that it creates an opportunity for the exercise of police discretion which is mainly uncontrolled, with potentialmisconduct on the part of law enforcement officials and the subversion of public trust in the reasonableness of the criminal justice system. Consequently, methods by which the exercise of discretion in the system of trapping can be justified are investigated, since there is room for discretionary powers which are properly circumscribed, structured and controlled. The main methods of control over the exercise of discretion in the system of trapping, namely the exclusion of evidence and a defence in a criminal proceeding, are fully investigated with reference to English, American and Canadian law. Having considered the above, the conclusion is advanced that legislative structuring of the exercise of discretion in the system of trapping offers the most effective solution for most of the problems underlying the system. The only acceptable basis on which the system can function, is to define the scope of acceptable trapping techniques and the confines within which law enforcement officials may prevail on someone to commit a crime. This must be done by means of legislation. Accordingly, there is a need for codification of standards which have to be complied with before any trapping operation may commence. / Criminal & Procedural Law / LL.D. (Criminal & Procedural Law)

Text in Afrikaans / Alhoewel die lokvalstelsel as misdaadbekampingsmetode lank reeds bestaan, is die toepassing daarvan nog altyd kontroversieE!I. Hierdie omstredenheid is die laaste paar jaar op die voorgrond gedryf deur 'n Regskommissie-ondersoek, sowel as deur die aanvaarding van 'n Handves van Menseregte. Ondersoek word ingestel na hierdie omstredenheid deur te kyk na die inhoud en toepassing van die stelsel, sowel as na die rol wat private persona, die polisie en die hot by die stelsel speeL Die gevolgtrekking waartoe gekom word, is dat die omstredenheid van die stelsel te danke is aan die feit dat dit verband hou met pro-aktiewe regshandhawing, wat in wese bestaan uit die gebruik van misleiding ten einde die pleging van 'n misdaad teweeg te bring. Die probleem met pro-aktiewe regshandhawing is dat dit 'n geleentheid skep vir die uitoefening van polisiediskresie wat grootliks sonder beheer geskied, met potensiele wanoptrede aan die kant van regshandhawers en die ondermyning van die publiek se vertroue in die billikheid van die strafregspleging. Ondersoek word gevolglik ingestel na metodes om diskresie-uitoefening by die lokvalstelsel te regverdig, aangesien daar wei ruimte is vir diskresionere magte wat behoorlik begrens, gestruktureer en gekontroleer is. Die vernaamste metodes van beheer oor diskresie­ uitoefening by die lokvalstelsel, naamlik die uitsluiting van getuienis en weerstand in 'n strafgeding, word grondig ondersoek met verwysing na die Engelse-, Amerikaanse- en Kanadese reg. Dit is egter die uitgangspunt van hierdie proefskrif dat wetgewende strukturering van diskresie-uitoefening by die lokvalstelsel die mees effektiewe oplossing bied vir meeste van die problema van die stelsel. Die enigste aanvaarbare basis waarop die lokvalstelsel kan funksioneer, is om deur middel van wetgewing die trefwydte van toelaatbare lokvaltegnieke en die beperkinge waarbinne regshandhawers regsonderdane mag beweeg om misdade te pleeg, te definieer. Daar is dus 'n behoefte aan die kodifisering van standaarde waaraan voldoen moet word voordat enige lokvaloperasie behoort te begin. / Although the system of trapping has long been used as a method of preventing crime, its employment has always been controversial. In the recent past, this controversy has come to the front due to an investigation by the South African Law Commission and the acceptance of a Bill of Rights. This thesis investigates this controversy by looking at the contents and application of the system, as well as the role which private persons, the police and the court play in the system. The conclusion arrived at, is that the controversy surrounding the system is due to the fact that it has to do with pro-active law enforcement, which consists of the use of deception to induce the performance of a criminal act. The problem with pro-active law enforcement is that it creates an opportunity for the exercise of police discretion which is mainly uncontrolled, with potentialmisconduct on the part of law enforcement officials and the subversion of public trust in the reasonableness of the criminal justice system. Consequently, methods by which the exercise of discretion in the system of trapping can be justified are investigated, since there is room for discretionary powers which are properly circumscribed, structured and controlled. The main methods of control over the exercise of discretion in the system of trapping, namely the exclusion of evidence and a defence in a criminal proceeding, are fully investigated with reference to English, American and Canadian law. Having considered the above, the conclusion is advanced that legislative structuring of the exercise of discretion in the system of trapping offers the most effective solution for most of the problems underlying the system. The only acceptable basis on which the system can function, is to define the scope of acceptable trapping techniques and the confines within which law enforcement officials may prevail on someone to commit a crime. This must be done by means of legislation. Accordingly, there is a need for codification of standards which have to be complied with before any trapping operation may commence. / Criminal and Procedural Law / LL.D. (Criminal & Procedural Law)

Drop impact is a canonical problem in fluid mechanics, with numerous applications in industrial as well as natural phenomena. The extremely simple initial configuration of the experiment can produce a very large variety of fast and complex dynamics. Scientific progress was made in parallel with major improvements in imaging and computational technologies. Most recently, high-speed imaging video cameras have opened the exploration of new phenomena occurring at the micro-second scale, and parallel computing allowed realistic direct numerical simulations of drop impacts. We combine these tools to bring a new understanding of two fundamental aspects of drop impacts: splashing and air entrapment. The early dynamics of a drop impacting on a liquid pool at high velocity produces an ejecta sheet, emerging horizontally in the neck between the drop and the pool. We show how the interaction of this thin liquid sheet with the air, the drop or the pool, can produce micro-droplets and bubble rings. Then we detail how the breakup of the air film stretched between the drop and the pool for lower impact velocities can produce a myriad of micro-bubbles.

Research investigating the role of two evolutionary constructs – perceptions of defeat and entrapment – in various psychological problems and processes has burgeoned over recent years. This meta-analysis quantitatively summarised the findings from 38 studies (11,343 participants) which examined relationships between perceptions of defeat and entrapment and four psychological problems commonly encountered in NHS clinical services: depression, suicidality, anxiety problems and Post-Traumatic Stress Disorder (PTSD). All correlations between defeat and entrapment and the four psychological problems were large by Cohen’s (1988) criterion. Correlations between defeat and entrapment and depression were larger than those for the other psychological problem groups, and significantly larger than those for anxiety problems and PTSD. The magnitude of the observed correlations introduces the possibility that defeat and entrapment, and perhaps other evolutionary constructs, may be integral components or driving forces behind all psychological problems. A robust approach to sensitivity analysis provided confidence that the population effect size estimates are robust and were not severely inflated by unpublished studies not included in the meta-analysis. As there was no significant between-study heterogeneity, moderator analyses were undertaken on an exploratory basis. Findings are generally consistent with theoretical predictions from the Involuntary Defeat Strategy, the theoretical model underpinning the literature. Overall, perceptions of defeat and entrapment appear to be strong risk factors for the four psychological problems examined, perhaps representing transdiagnostic processes that are common across various psychological problems. The potential role of defeat and entrapment in mental health assessment, formulation, intervention and evaluation, is considered in detail and limitations of this meta-analysis and of the literature on which it is based are discussed, highlighting areas of research where future work is needed.