Dissipative parametric modulation instability and pattern formation in nonlinear optical systems

We present the essential features of the dissipative parametric instability, in the universal complex Ginzburg- Landau equation. Dissipative parametric instability is excited through a parametric modulation of frequency dependent losses in a zig-zag fashion in the spectral domain. Such damping is introduced respectively for spectral components in the +ΔF and in the -ΔF region in alternating fashion, where F can represent wavenumber or temporal frequency depending on the applications. Such a spectral modulation can destabilize the homogeneous stationary solution of the system leading to growth of spectral sidebands and to the consequent pattern formation: both stable and unstable patterns in one- and in two-dimensional systems can be excited. The dissipative parametric instability provides an useful and interesting tool for the control of pattern formation in nonlinear optical systems with potentially interesting applications in technological applications, like the design of mode- locked lasers emitting pulse trains with tunable repetition rate; but it could also find realizations in nanophotonics circuits or in dissipative polaritonic Bose-Einstein condensates.

Self-pulsating nonlinear systems via dissipative parametric instability

The recently discovered dissipative parametric instability is presented in the framework of the universal complex Ginzburg-Landau equation. The pattern formation associated with the instability is discussed in connection to the relevant applications in nonlinear photonics especially as a new tool for pulsed lasers design.

Topoisomerase 1 (Top1)-associated Genome Instability in Yeast: Effects of Persistent Cleavage Complexes or Increased Top1 Levels

Topoisomerase 1 (Top1), a Type IB topoisomerase, functions to relieve transcription- and replication-associated torsional stress in DNA. Top1 cleaves one strand of DNA, covalently associates with the 3’ end of the nick to form a Top1-cleavage complex (Top1cc), passes the intact strand through the nick and finally re-ligates the broken strand. The chemotherapeutic drug, Camptothecin, intercalates at a Top1cc and prevents the crucial re-ligation reaction that is mediated by Top1, resulting in the conversion of a nick to a toxic double-strand break during DNA replication or the accumulation of Top1cc. This mechanism of action preferentially targets rapidly dividing tumor cells, but can also affect non-tumor cells when patients undergo treatment. Additionally, Top1 is found to be elevated in numerous tumor tissues making it an attractive target for anticancer therapies. We investigated the effects of Top1 on genome stability, effects of persistent Top1-cleavage complexes and elevated Top1 levels, in Saccharomyces cerevisiae. We found that increased levels of the Top1cc resulted in a five- to ten-fold increase in reciprocal crossovers, three- to fifteen fold increase in mutagenesis and greatly increased instability within the rDNA and CUP1 tandem arrays. Increased Top1 levels resulted in a fifteen- to twenty-two fold increase in mutagenesis and increased instability in rDNA locus. These results have important implications for understanding the effects of CPT and elevated Top1 levels as a chemotherapeutic agent.

Electronic Instability and Anharmonicity in SnSe

The binary compound SnSe exhibits record high thermoelectric performance, largely because of its very low thermal conductivity. The origin of the strong phonon anharmonicity leading to the low thermal conductivity of SnSe is investigated through first-principles calculations of the electronic structure and phonons. It is shown that a Jahn-Teller instability of the electronic structure is responsible for the high-temperature lattice distortion between the Cmcm and Pnma phases. The coupling of phonon modes and the phase transition mechanism are elucidated, emphasizing the connection with hybrid improper ferroelectrics. This coupled instability of electronic orbitals and lattice dynamics is the origin of the strong anharmonicity causing the ultralow thermal conductivity in SnSe. Exploiting such bonding instabilities to generate strong anharmonicity may provide a new rational to design efficient thermoelectric materials.

Aspects of postural alignment and postural control relevant for the evaluation and the treatment of idiopathic scoliosis patients

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Oxidative DNA Damage Modulates Trinucleotide Repeat Instability Via DNA Base Excision Repair

Trinucleotide repeat (TNR) expansion is the cause of more than 40 types of human neurodegenerative diseases such as Huntington’s disease. Recent studies have linked TNR expansion with oxidative DNA damage and base excision repair (BER). In this research, we provided the first evidence that oxidative DNA damage can induce CAG repeat deletion/contraction via BER. We found that BER of an oxidized DNA base lesion, 8-oxoguanine in a CAG repeat tract, resulted in the formation of a CTG hairpin at the template strand. DNA polymerase β (pol b) then skipped over the hairpin creating a 5’-flap that was cleaved by flap endonuclease 1 (FEN1) leading to CAG repeat deletion. To further investigate whether BER may help to shorten an expanded TNR tract, we examined BER in a CAG repeat hairpin loop. We found that 8-oxoguanine DNA glycosylase removed the oxidized base located in the loop region of the hairpin leaving an abasic site. Apurinic/apyrimidinic (AP) endonuclease 1 then incised the 5’-end of the abasic site leaving a nick in the loop. This further converted the hairpin into an intermediate with a 3’-flap and a 5’-flap. As a 5’-3’ endonuclease, FEN1 cleaved the 5’-flap, whereas a 3’-5’ endonuclease, Mus81/Eme1, removed the 3’-flap. The coordination between FEN1 and Mus81/Eme1 ultimately resulted in removal of a CAG repeat hairpin attenuating or preventing TNR expansion. To further explore if pol β bypass of an oxidized base lesion, 5’,8-cyclodeoxyadenosine, may affect TNR instability, we examined pol β DNA synthesis in bypassing this base lesion and found that the lesion preferentially induced TNR deletion during BER and Okazaki fragment maturation. The repeat deletion was mediated by the formation of a loop in the template strand induced specifically by the damage. Pol β then skipped over the loop structure creating a 5’-flap that was efficiently removed by FEN1 leading to repeat deletion. Our study demonstrates that pol β-mediated BER plays an important role in mediating TNR deletion and removing a TNR hairpin to prevent TNR expansion. Our research provides a molecular basis for further developing BER as a target for prevention and treatment of neurodegenerative diseases caused by TNR expansion.

Hidroginástica postural : Reflexões e ações

A hidroginástica é uma prática de exercício física praticada em todo o mundo e caracteriza-se por ser de baixo impacto. O presente estudo tem como foco de açao o projeto de extensao intitulado "Hidroginástica Postural Inter geracional para todos" que objetiva oferecer um espaço de hidroginástica a comunidade de Santa Maria\RS. A finalidade desse estudo consiste em relatar a intervençao profissional junto ao projeto de Hidroginástica postural. A metodologia do trabalho consiste em um relato de experiência de como as aulas de hidroginástica sao desenvolvidas no projeto. O projeto de extensao "Hidroginástica Inter geracional para todos" oferta um espaço de exercício no meio líquido a fim de contribuir com a saúde de seus praticantes e atua diretamente na melhoria do quadro clínico de seus alunos. Além do mais, esse projeto possibilita a inserçao de acadêmicos no meio profissional, promovendo um espaço de açao\reflexao sobre as aulas de hidroginástica, contribuindo como o processo formativo dos acadêmicos de Educaçao Física

Hidroginástica postural : Reflexões e ações

A hidroginástica é uma prática de exercício física praticada em todo o mundo e caracteriza-se por ser de baixo impacto. O presente estudo tem como foco de açao o projeto de extensao intitulado "Hidroginástica Postural Inter geracional para todos" que objetiva oferecer um espaço de hidroginástica a comunidade de Santa Maria\RS. A finalidade desse estudo consiste em relatar a intervençao profissional junto ao projeto de Hidroginástica postural. A metodologia do trabalho consiste em um relato de experiência de como as aulas de hidroginástica sao desenvolvidas no projeto. O projeto de extensao "Hidroginástica Inter geracional para todos" oferta um espaço de exercício no meio líquido a fim de contribuir com a saúde de seus praticantes e atua diretamente na melhoria do quadro clínico de seus alunos. Além do mais, esse projeto possibilita a inserçao de acadêmicos no meio profissional, promovendo um espaço de açao\reflexao sobre as aulas de hidroginástica, contribuindo como o processo formativo dos acadêmicos de Educaçao Física

Hidroginástica postural : Reflexões e ações

A hidroginástica é uma prática de exercício física praticada em todo o mundo e caracteriza-se por ser de baixo impacto. O presente estudo tem como foco de açao o projeto de extensao intitulado "Hidroginástica Postural Inter geracional para todos" que objetiva oferecer um espaço de hidroginástica a comunidade de Santa Maria\RS. A finalidade desse estudo consiste em relatar a intervençao profissional junto ao projeto de Hidroginástica postural. A metodologia do trabalho consiste em um relato de experiência de como as aulas de hidroginástica sao desenvolvidas no projeto. O projeto de extensao ?Hidroginástica Inter geracional para todos? oferta um espaço de exercício no meio líquido a fim de contribuir com a saúde de seus praticantes e atua diretamente na melhoria do quadro clínico de seus alunos. Além do mais, esse projeto possibilita a inserçao de acadêmicos no meio profissional, promovendo um espaço de açao\reflexao sobre as aulas de hidroginástica, contribuindo como o processo formativo dos acadêmicos de Educaçao Física

Earnings Variability and Earnings Instability of Women and Men in Canada: How Do the 1990's Compare to the 1980's (Working Paper 25)

It seems to be generally assumed that earnings instability has increased in the last decade or so, as earnings inequality has widened, but is this indeed the case, and if so, to what degree? This paper builds on earlier U.S. work to look at the total variance in individuals’ earnings with a focus on the distinction between permanent earnings variation associated with factors such as human capital investments or other persistent worker attributes, and transitory earnings variation or instability for a given individual from one year to another. We find that there was an increase in overall earnings variability, especially for men, but that the greatest part of this increase was driven by the permanent component – that is, by a widening dispersion of (life-cycle) earnings differentials across workers. The increased volatility of workers’ earnings about their life-cycle earnings profiles played a secondary role in the overall increase in men’s earnings variability, whereas for women this effect was very small or even worked in the opposite direction (depending on the particular age group). Patterns by age and region are also investigated.

Kelvin-Helmholtz instability in solar chromospheric jets: theory and observation

Using data obtained by the high-resolution CRisp Imaging SpectroPolarimeter instrument on the Swedish 1 m Solar Telescope, we investigate the dynamics and stability of quiet-Sun chromospheric jets observed at the disk center. Small-scale features, such as rapid redshifted and blueshifted excursions, appearing as high-peed jets in the wings of the Hα line, are characterized by short lifetimes and rapid fading without any descending behavior. To study the theoretical aspects of their stability without considering their formation mechanism, we model chromospheric jets as twisted magnetic flux tubes moving along their axis, and use the ideal linear incompressible magnetohydrodynamic approximation to derive the governing dispersion equation. Analytical solutions of the dispersion equation indicate that this type of jet is unstable to Kelvin–Helmholtz instability (KHI), with a very short (few seconds) instability growth time at high upflow speeds. The generated vortices and unresolved turbulent flows associated with the KHI could be observed as a broadening of chromospheric spectral lines. Analysis of the Hα line profiles shows that the detected structures have enhanced line widths with respect to the background. We also investigate the stability of a larger-scale Hα jet that was ejected along the line of sight. Vortex-like features, rapidly developing around the jet’s boundary, are considered as evidence of the KHI. The analysis of the energy equation in the partially ionized plasma shows that ion–neutral collisions may lead to fast heating of the KH vortices over timescales comparable to the lifetime of chromospheric jets.

This Time is Different: Causes and Consequences of British Banking Instability over the Long Run

This paper addresses three questions: (1) How severe were the episodes of banking instability
experienced by the UK over the past two centuries? (2) What have been the macroeconomic
indicators of UK banking instability? and (3) What have been the consequences of UK banking
instability for the cost of credit? Using a unique dataset of bank share prices from 1830 to 2010
to assess the stability of the UK banking system, we find that banking instability has grown more
severe since the 1970s. We also find that interest rates, inflation, lending growth, and equity
prices are consistent macroeconomic indicators of UK banking instability over the long run.
Furthermore, utilising a unique dataset of corporate-bond yields for the period 1860 to 2010, we
find that there is a significant long-run relationship between banking instability and the creditrisk
premium faced by businesses.

Colete Instrumentado para reeducação postural

A coluna vertebral é um dos elementos do corpo humano que mais lesões e danos irreparáveis sofre. Segundo a organização mundial de saúde, 85% da população mundial sofre de dores na coluna e estas representam mais de 50% das causas de incapacidade física transitória ou perma-nente em idade laboral. Uma das principais causas desses danos prende-se com uma postura cor-poral incorreta o que provoca alterações nas estruturas da coluna. Nesse contexto, a existência de um dispositivo capaz de avaliar em tempo real a postura corporal, e que simultaneamente, alerte para a ocorrência de posturas incorretas assume-se como uma mais-valia para a prevenção deste tipo de situações. Neste trabalho é proposto um “colete” instrumentado para reeducação postural, capaz de dotar os utilizadores de informação relativa à sua postura ao nível da coluna vertebral. O dispositivo é com-posto por um conjunto de sensores IMU, estrategicamente colocados para melhor caraterização do perfil da coluna. Os dados sensoriais são classificados por uma unidade de processamento central. Nesta unidade, além de outras funcionalidades, está implementado um classificador cujos dados de treino foram obtidos numa outra tese de mestrado desenvolvida paralelamente. Em caso de postura incorreta, os utilizadores serão alertados através de um sinal sonoro e vibratório. O sistema funciona como um wearable, stand-alone, ou seja, não necessita de qualquer tipo de aplicação ou componente externo. Contudo, foi desenvolvida uma API cujo objetivo é potenciar a utilização do dispositivo noutro tipo de aplicações. Para demonstrar a aplicabilidade da API, foram desenvolvidas duas aplicações, uma para computador e outra para dispositivos móveis Android. Estas permitem monitorizar em tempo real o perfil da coluna, lançar notificações de postura incor-reta, entre outros. O protótipo e as aplicações foram testados em contexto de aula por 10 indivíduos em dois momentos de monitorização distintos, um primeiro momento sem qualquer tipo de feedback ativo e um segundo com feedback ativo. Estes testes serviram para validação de usabilidade, fiabilidade e depuração de erros. Os testes demonstraram que o sistema possui elevado nível de fiabilidade na classificação da postura promovendo a reeducação postural. A totalidade dos sujeitos apresentaram um decrés-cimo percentual no tempo passado com postura incorreta no segundo dia de testes face ao dia de referência em que os sistemas de feedback se encontravam desligados. Em alguns casos, a diminuição atingiu valores próximos de 80%.