Symmetry breaking perturbations and strange attractors

The asymmetrically forced, damped Duffing oscillator is introduced as a prototype model for analyzing the homoclinic tangle of symmetric dissipative systems with \textit{symmetry breaking} disturbances. Even a slight fixed asymmetry in the perturbation may cause a substantial change in the asymptotic behavior of the system, e.g. transitions from two sided to one sided strange attractors as the other parameters are varied. Moreover, slight asymmetries may cause substantial asymmetries in the relative size of the basins of attraction of the unforced nearly symmetric attracting regions. These changes seems to be associated with homoclinic bifurcations. Numerical evidence indicates that \textit{strange attractors} appear near curves corresponding to specific secondary homoclinic bifurcations. These curves are found using analytical perturbational tools

Será a insuficiência renal uma contra-indicação relativa para as biópsias broncoscópicas?

Resumo: Em 1977, Cunningham e col. demonstraram que, nos doentes urémicos sujeitos a broncofibroscopia com biopsias, 45% tiveram hemorragias.Actualmente, não há trabalhos publicados que avaliem este risco.Os autores resolveram avaliar os processos de todas as broncofibroscopias realizadas entre 1997 e 2002 no Hospital de Bellvue, Nova Iorque, registando os resultados da ureia, da creatinina, do hemograma, do estudo da coagulação, do tipo de biópsias executadas da pré-medicação e das complicações.Os doentes eram incluídos nos trabalhos desde que tivessem a ureia superior ou igual a 30 mg/dl e/ou a creatinina superior ou igual a 2,0 mg/dl. Perante estes critérios foram incluídos no estudo 72 doentes.Vinte e cinco doentes dos 72(35 %) foram submetidos a biopsias. Sete dos 25 (28 %) foram hemodializados e 18 dos 25(72 %) não foram hemodializados. Todos os doentes hemodializados foram submetidos à broncofibroscopia 24 horas depois da hemodiálise e foram submetidos a uma perfusão de desmopressina pré-broncofibroscopia, e um doente com coagulopatia recebeu plaquetas e plasma fresco.Os doentes hemodializados submetidos a biópsias tinham valores de ureia que oscilavam entre 31-65 mg/ /dl e valores de creatinina que oscilavam entre 5,2-18,7 mg/dl, e o único doente deste grupo que fez punção aspirativa transbrônquica tinha uma ureia de 32 mg/dl e uma creatinina de 4,3 mg/dl.Em doze dos 18 doentes não submetidos a hemodiálise e submetidos a biópsias, os valores de ureia oscilavam entre 20-69 mg/dl e os valores de creatinina entre 0,9-2,5 mg/dl. Deste grupo, os quatro doentes que foram submetidos a punção aspirativa transbrônquica tinham valores de ureia entre 20-62 mg/dl e valores de creatinina entre 1,1-4,5 mg/dl. Os dois doentes sujeitos a biópsias e punção aspirativa transbrônquica tinham valores de ureia de 30 e 35 mg/dl e valores de de 1,4 e 1,5 mg/dl. Um dos 25 doentes não hemodializados teve uma complicação major, hemorragia maciça que obrigou a intervenção. Um outro deste mesmo grupo teve apenas uma hemorragia minor.Não houve complicações nos doentes hemodializados.Estes resultados sugerem que não há tantas complicações como seria de esperar nos doentes com insuficiência renal, como demonstrou Cullingam e col. em 1977. Mostram que não há complicações nos doentes hemodializados e sujeitos a uma perfusão de desmopressina antes de ser efectuada a broncofibroscopia.Estes dados obrigam à realização de novos estudos para avaliar de facto se as biópsias broncoscópicas são uma contra-indicação relativa na insuficiência renal. Palavras-chave: Broncofibroscopia, biópsias broncoscópicas, insuficiência renal, complicações hemorrágica

Unlocking biomarker discovery: Large scale application of aptamer proteomic technology for early detection of lung cancer

Lung cancer is the leading cause of cancer deaths, because ~84% of cases are diagnosed at an advanced stage. Worldwide in 2008, ~1.5 million people were diagnosed and ~1.3 million died – a survival rate unchanged since 1960. However, patients diagnosed at an early stage and have surgery experience an 86% overall 5-year survival. New diagnostics are therefore needed to identify lung cancer at this stage. Here we present the first large scale clinical use of aptamers to discover blood protein biomarkers in disease with our breakthrough proteomic technology. This multi-center case-control study was conducted in archived samples from 1,326 subjects from four independent studies of non-small cell lung cancer (NSCLC) in long-term tobacco-exposed populations. We measured >800 proteins in 15uL of serum, identified 44 candidate biomarkers, and developed a 12-protein panel that distinguished NSCLC from controls with 91% sensitivity and 84% specificity in a training set and 89% sensitivity and 83% specificity in a blinded, independent verification set. Performance was similar for early and late stage NSCLC. This is a significant advance in proteomics in an area of high clinical need

Approximating multi-dimensional Hamiltonian flows by billiards

Consider a family of smooth potentials $V_{\epsilon}$, which, in the limit $\epsilon\to0$, become a singular hard-wall potential of a multi-dimensional billiard. We define auxiliary billiard domains that asymptote, as $\epsilon\to0$ to the original billiard, and provide asymptotic expansion of the smooth Hamiltonian solution in terms of these billiard approximations. The asymptotic expansion includes error estimates in the $C^{r}$ norm and an iteration scheme for improving this approximation. Applying this theory to smooth potentials which limit to the multi-dimensional close to ellipsoidal billiards, we predict when the separatrix splitting persists for various types of potentials

Enrichment of lung microbiome with supraglottic taxa is associated with increased pulmonary inflammation

BACKGROUND: The lung microbiome of healthy individuals frequently harbors oral organisms. Despite evidence that microaspiration is commonly associated with smoking-related lung diseases, the effects of lung microbiome enrichment with upper airway taxa on inflammation has not been studied. We hypothesize that the presence of oral microorganisms in the lung microbiome is associated with enhanced pulmonary inflammation. To test this, we sampled bronchoalveolar lavage (BAL) from the lower airways of 29 asymptomatic subjects (nine never-smokers, 14 former-smokers, and six current-smokers). We quantified, amplified, and sequenced 16S rRNA genes from BAL samples by qPCR and 454 sequencing. Pulmonary inflammation was assessed by exhaled nitric oxide (eNO), BAL lymphocytes, and neutrophils. RESULTS: BAL had lower total 16S than supraglottic samples and higher than saline background. Bacterial communities in the lower airway clustered in two distinct groups that we designated as pneumotypes. The rRNA gene concentration and microbial community of the first pneumotype was similar to that of the saline background. The second pneumotype had higher rRNA gene concentration and higher relative abundance of supraglottic-characteristic taxa (SCT), such as Veillonella and Prevotella, and we called it pneumotype(SCT). Smoking had no effect on pneumotype allocation, α, or β diversity. Pneumotype(SCT) was associated with higher BAL lymphocyte-count (P= 0.007), BAL neutrophil-count (P= 0.034), and eNO (P= 0.022). CONCLUSION: A pneumotype with high relative abundance of supraglottic-characteristic taxa is associated with enhanced subclinical lung inflammation

Domain Walls and the Creation of Strings

The phenomenon of creation of strings, occurring when particles pass through a domain wall and related to the Hanany-Witten effect via dualities, is discussed in ten and nine dimensions. We consider both the particle actions in massive backgrounds as well as the 1/4-supersymmetric particle-string-domain wall supergravity solutions and discuss their physical interpretation. In 10D we discuss the D0-F1-D8 system in massive IIA theory while in 9D the SL(2,R)-generalisation is constructed. It consists of (p,q)-particles, (r,s)-strings and the double domain wall solution of the three different 9D gauged supergravities where a subgroup of SL(2,R) is gauged.Comment: v1: 22 pages, 3 figures. v2: footnote and reference adde

Interaction and filling induced quantum phases of dual Mott insulators of bosons and fermions

Many-body effects are at the very heart of diverse phenomena found in condensed-matter physics. One striking example is the Mott insulator phase where conductivity is suppressed as a result of a strong repulsive interaction. Advances in cold atom physics have led to the realization of the Mott insulating phases of atoms in an optical lattice, mimicking the corresponding condensed matter systems. Here, we explore an exotic strongly-correlated system of Interacting Dual Mott Insulators of bosons and fermions. We reveal that an inter-species interaction between bosons and fermions drastically modifies each Mott insulator, causing effects that include melting, generation of composite particles, an anti-correlated phase, and complete phase-separation. Comparisons between the experimental results and numerical simulations indicate intrinsic adiabatic heating and cooling for the attractively and repulsively interacting dual Mott Insulators, respectively

An SU(N) Mott insulator of an atomic Fermi gas realized by large-spin Pomeranchuk cooling

The Hubbard model, containing only the minimum ingredients of nearest neighbor hopping and on-site interaction for correlated electrons, has succeeded in accounting for diverse phenomena observed in solid-state materials. One of the interesting extensions is to enlarge its spin symmetry to SU(N>2), which is closely related to systems with orbital degeneracy. Here we report a successful formation of the SU(6) symmetric Mott insulator state with an atomic Fermi gas of ytterbium (173Yb) in a three-dimensional optical lattice. Besides the suppression of compressibility and the existence of charge excitation gap which characterize a Mott insulating phase, we reveal an important difference between the cases of SU(6) and SU(2) in the achievable temperature as the consequence of different entropy carried by an isolated spin. This is analogous to Pomeranchuk cooling in solid 3He and will be helpful for investigating exotic quantum phases of SU(N) Hubbard system at extremely low temperatures.Comment: 20 pages, 6 figures, to appear in Nature Physic

High field level crossing studies on spin dimers in the low dimensional quantum spin system Na2_2T2_2(C2_2O4_4)3_3(H2_2O)2_2 with T=Ni,Co,Fe,Mn

In this paper we demonstrate the application of high magnetic fields to study the magnetic properties of low dimensional spin systems. We present a case study on the series of 2-leg spin-ladder compounds Na$_2$T$_2$(C$_2$O$_4$)$_3$(H$_2$O)$_2$ with T = Ni, Co, Fe and Mn. In all compounds the transition metal is in the $T^{2+}$ high spin configuation. The localized spin varies from S=1 to 3/2, 2 and 5/2 within this series. The magnetic properties were examined experimentally by magnetic susceptibility, pulsed high field magnetization and specific heat measurements. The data are analysed using a spin hamiltonian description. Although the transition metal ions form structurally a 2-leg ladder, an isolated dimer model consistently describes the observations very well. This behaviour can be understood in terms of the different coordination and superexchange angles of the oxalate ligands along the rungs and legs of the 2-leg spin ladder. All compounds exhibit magnetic field driven ground state changes which at very low temperatures lead to a multistep behaviour in the magnetization curves. In the Co and Fe compounds a strong axial anisotropy induced by the orbital magnetism leads to a nearly degenerate ground state and a strongly reduced critical field. We find a monotonous decrease of the intradimer magnetic exchange if the spin quantum number is increased

Upotreba živinih mjernih uređaja u zdravstvenim ustanovama u Hrvatskoj

In 2009, we conducted a survey to assess the use of mercury-based thermometers and sphygmomanometers and their disposal in Croatian healthcare facilities. The questionnaire addressing the use of mercury-based medical devices, waste management, preferences between mercury-based and electronic devices, and the knowledge on mercury toxicity was filled by ward nurses affiliated with 40 (71.4 %) out of 56 contacted healthcare facilities. Only one of these facilities had given up the use of mercury-containing medical devices at the time. As many as 84.6 % of the nurses believed that broken devices did not increase the risk of mercury exposure, even though 90 % claimed they were aware of mercury toxicity. In fact, 69.4 % of the nurses preferred mercury-containing devices on account of their precision and reliability and because they received little training in the use of electronic devices. Breaking of thermometers and sphygmomanometers is common in healthcare facilities. The number of broken thermometers and sphygmomanometers was estimated to 278 and fi ve per month, respectively. Only 18 (46.2 %) of the surveyed healthcare facilities claimed to have had a proper disposal procedure for mercury from broken devices. Nurses, who most often handle these devices and collect mercury spills, are primarily exposed to mercury vapours via inhalation. Croatia has adopted the EU Directive 76/769/EEC intended to reduce mercury exposure in the living and working environment. Our survey suggests that all healthcare professionals need training in proper management of broken mercury-based medical devices, nurses in particular. To reduce the risk of exposure, all Croatian healthcare facilities should implement guidelines for staff protection and programmes to gradually replace mercury-based with electronic devices.Živa je štetni čimbenik izravno povezan s provođenjem zdravstvene zaštite. Tijekom 2009. provedeno je istraživanje u zdravstvenim ustanovama RH, s ciljem procjene uporabe živinih mjernih instrumenata, toplomjera i tlakomjera te načina odlaganja razbijenih uređaja. Upitnik o uporabi živinih uređaja, zbrinjavanju otpada, sklonostima uporabi živinih, odnosno elektroničkih mjernih uređaja te pitanja o poznavanju toksičnosti žive, ispunile su odjelne medicinske sestre iz 40 (71,4 %) od 56 zdravstvenih ustanova. Samo u jednoj ustanovi živini se mjerni uređaji uopće ne rabe. Čak 84,6 % ispitanica smatra da nisu dodatno izložene živi iz razbijenih uređaja, iako je 90 % svjesno toksičnosti Hg. Zbog njihove preciznosti, pouzdanosti i nedostatka edukacije o uporabi i održavanju elektroničkih uređaja prednost uporabi živinih uređaja daje 69,4 % medicinskih sestara. Razbijanje toplomjera i tlakomjera čest je incident u zdravstvenim ustanovama. Procijenjeni broj mjesečno razbijenih toplomjera bio je do 278, a razbijenih tlakomjera do 5. U samo 18 (46,2 %) ustanova pravilno se odlagala živa iz razbijenih uređaja. Medicinske sestre koje najčešće rukuju uređajima i prikupljaju živu najizloženije su živinim parama putem inhalacije. U Hrvatskoj su doneseni pravni akti s namjerom smanjenja prisutnosti žive u životnom i radnom okolišu. Time je stupila na snagu EU direktiva 76/769/EEZ-a o smanjenju proizvodnje i prometa uređaja koji ju sadržavaju. Rezultati upućuju na potrebu edukacije svih zdravstvenih radnika, posebno medicinskih sestara, o zbrinjavanju razbijenih živinih mjernih uređaja. Radi smanjenja potencijalne izloženosti i osiguranja boljih zdravstvenih uvjeta na radnome mjestu sve hrvatske zdravstvene ustanove trebaju provoditi smjernice za zaštitu radnika i programe za smanjenje uporabe žive uporabom zamjenskih toplomjera i tlakomjera dostupnih na tržištu