Inducing Transport in a Dissipation-Free Lattice with Super Bloch Oscillations

Particles in a perfect lattice potential perform Bloch oscillations when subject to a constant force, leading to localization and preventing conductivity. For a weakly-interacting Bose-Einstein condensate (BEC) of Cs atoms, we observe giant center-of-mass oscillations in position space with a displacement across hundreds of lattice sites when we add a periodic modulation to the force near the Bloch frequency. We study the dependence of these "super" Bloch oscillations on lattice depth, modulation amplitude, and modulation frequency and show that they provide a means to induce linear transport in a dissipation-free lattice. Surprisingly, we find that, for an interacting quantum system, super Bloch oscillations strongly suppress the appearance of dynamical instabilities and, for our parameters, increase the phase-coherence time by more than a factor of hundred.Comment: 4 pages, 5 figure

Optical echo in photonic crystals

The dynamics of photonic wavepacket in the effective oscillator potential is studied. The oscillator potential is constructed on a base of one dimensional photonic crystal with a period of unit cell adiabatically varied in space. The structure has a locally equidistant discrete spectrum. This leads to an echo effect, i.e. the periodical reconstruction of the packet shape. The effect can be observed in a nonlinear response of the system. Numerical estimations for porous-silicon based structures are presented for femtosecond Ti:Sapphire laser pump.Comment: 4 page

Higher serum levels of periostin and the risk of exacerbations in moderate asthmatics

BACKGROUND: In asthma, exacerbations and poor disease control are linked to airway allergic inflammation. Serum periostin has been proposed as a systemic biomarker of eosinophilic inflammation. This pilot study aims at evaluating whether in patients with moderate asthma, higher baseline levels of serum periostin are associated with a greater risk of exacerbation. METHODS: Fifteen outpatients with moderate allergic asthma were recruited. Serum concentrations of periostin were assessed (ELISA) at baseline, and the frequency of asthma exacerbations was recorded during a one-year follow-up. RESULTS: Patients (M/F: 10/5, mean age of 47.6\u2009\ub1\u200911.0 years) had mean ACQ score of 5.5\u2009\ub1\u20094.2 and FEV1%pred of 81.9\u2009\ub1\u200921.7 %. Baseline serum levels of periostin did not correlate with lung function parameters, nor with the ACQ score (p 650.05 for all analyses). Five subjects (33 % of the study group) reported one or more exacerbations during the following year. Baseline serum levels of periostin were significantly higher in subjects who experienced one or more exacerbations during the one year period of follow-up, compared with subjects with no exacerbations: median serum periostin level was 4047 ng/ml (range: 2231 to 4889 ng/ml) and 222 ng/ml (range 28.2 to 1631 ng/ml) respectively; p\u2009=\u20090.001. CONCLUSION: The findings of the present pilot study could form the basis for the design of larger studies aiming at developing strategies to identify asthmatic patients at risk for exacerbations

Optical properties of structurally-relaxed Si/SiO2_2 superlattices: the role of bonding at interfaces

We have constructed microscopic, structurally-relaxed atomistic models of Si/SiO$_2$ superlattices. The structural distortion and oxidation-state characteristics of the interface Si atoms are examined in detail. The role played by the interface Si suboxides in raising the band gap and producing dispersionless energy bands is established. The suboxide atoms are shown to generate an abrupt interface layer about 1.60 \AA thick. Bandstructure and optical-absorption calculations at the Fermi Golden rule level are used to demonstrate that increasing confinement leads to (a) direct bandgaps (b) a blue shift in the spectrum, and (c) an enhancement of the absorption intensity in the threshold-energy region. Some aspects of this behaviour appear not only in the symmetry direction associated with the superlattice axis, but also in the orthogonal plane directions. We conclude that, in contrast to Si/Ge, Si/SiO$_2$ superlattices show clear optical enhancement and a shift of the optical spectrum into the region useful for many opto-electronic applications.Comment: 11 pages, 10 figures (submitted to Phys. Rev. B

Physics of the Riemann Hypothesis

Physicists become acquainted with special functions early in their studies. Consider our perennial model, the harmonic oscillator, for which we need Hermite functions, or the Laguerre functions in quantum mechanics. Here we choose a particular number theoretical function, the Riemann zeta function and examine its influence in the realm of physics and also how physics may be suggestive for the resolution of one of mathematics' most famous unconfirmed conjectures, the Riemann Hypothesis. Does physics hold an essential key to the solution for this more than hundred-year-old problem? In this work we examine numerous models from different branches of physics, from classical mechanics to statistical physics, where this function plays an integral role. We also see how this function is related to quantum chaos and how its pole-structure encodes when particles can undergo Bose-Einstein condensation at low temperature. Throughout these examinations we highlight how physics can perhaps shed light on the Riemann Hypothesis. Naturally, our aim could not be to be comprehensive, rather we focus on the major models and aim to give an informed starting point for the interested Reader.Comment: 27 pages, 9 figure

Role of chymase in cigarette smoke-induced pulmonary artery remodeling and pulmonary hypertension in hamsters

<p>Abstract</p> <p>Background</p> <p>Cigarette smoking is an important risk factor for pulmonary arterial hypertension (PAH) in chronic obstructive pulmonary disease (COPD). Chymase has been shown to function in the enzymatic production of angiotensin II (AngII) and the activation of transforming growth factor (TGF)-β1 in the cardiovascular system. The aim of this study was to determine the potential role of chymase in cigarette smoke-induced pulmonary artery remodeling and PAH.</p> <p>Methods</p> <p>Hamsters were exposed to cigarette smoke; after 4 months, lung morphology and tissue biochemical changes were examined using immunohistochemistry, Western blotting, radioimmunoassay and reverse-transcription polymerase chain reaction.</p> <p>Results</p> <p>Our results show that chronic cigarette smoke exposure significantly induced elevation of right ventricular systolic pressures (RVSP) and medial hypertrophy of pulmonary arterioles in hamsters, concurrent with an increase of chymase activity and synthesis in the lung. Elevated Ang II levels and enhanced TGF-β1/Smad signaling activation were also observed in smoke-exposed lungs. Chymase inhibition with chymostatin reduced the cigarette smoke-induced increase in chymase activity and Ang II concentration in the lung, and attenuated the RVSP elevation and the remodeling of pulmonary arterioles. Chymostatin did not affect angiotensin converting enzyme (ACE) activity in hamster lungs.</p> <p>Conclusions</p> <p>These results suggest that chronic cigarette smoke exposure can increase chymase activity and expression in hamster lungs. The capability of activated chymase to induce Ang II formation and TGF-β1 signaling may be part of the mechanism for smoking-induced pulmonary vascular remodeling. Thus, our study implies that blockade of chymase might provide benefits to PAH smokers.</p

Elevated creatine kinase activity in primary hepatocellular carcinoma

BACKGROUND: Inconsistent findings have been reported on the occurrence and relevance of creatine kinase (CK) isoenzymes in mammalian liver cells. Part of this confusion might be due to induction of CK expression during metabolic and energetic stress. METHODS: The specific activities and isoenzyme patterns of CK and adenylate kinase (AdK) were analysed in pathological liver tissue of patients undergoing orthotopic liver transplantation. RESULTS: The brain-type, cytosolic BB-CK isoenzyme was detected in all liver specimens analysed. Conversely, CK activity was strongly increased and a mitochondrial CK (Mi-CK) isoenzyme was detected only in tissue samples of two primary hepatocellular carcinomas (HCCs). CONCLUSION: The findings do not support significant expression of CK in normal liver and most liver pathologies. Instead, many of the previous misconceptions in this field can be explained by interference from AdK isoenzymes. Moreover, the data suggest a possible interplay between p53 mutations, HCC, CK expression, and the growth-inhibitory effects of cyclocreatine in HCC. These results, if confirmed, could provide important hints at improved therapies and cures for HCC

Predicting survival after pulmonary metastasectomy for colorectal cancer: previous liver metastases matter

BACKGROUND: Few patients with lung metastases from colorectal cancer (CRC) are candidates for surgical therapy with a curative intent, and it is currently impossible to identify those who may benefit the most from thoracotomy. The aim of this study was to determine the impact of various parameters on survival after pulmonary metastasectomy for CRC. METHODS: We performed a retrospective analysis of 40 consecutive patients (median age 63.5 [range 33-82] years) who underwent resection of pulmonary metastases from CRC in our institution from 1996 to 2009. RESULTS: Median follow-up was 33 (range 4-139) months. Twenty-four (60%) patients did not have previous liver metastases before undergoing lung surgery. Median disease-free interval between primary colorectal tumor and development of lung metastases was 32.5 months. 3- and 5-year overall survival after thoracotomy was 70.1% and 43.4%, respectively. In multivariate analysis, the following parameters were correlated with tumor recurrence after thoracotomy; a history of previous liver metastases (HR = 3.8, 95%CI 1.4-9.8); and lung surgery other than wedge resection (HR = 3.0, 95%CI 1.1-7.8). Prior resection of liver metastases was also correlated with an increased risk of death (HR = 5.1, 95% CI 1.1-24.8, p = 0.04). Median survival after thoracotomy was 87 (range 34-139) months in the group of patients without liver metastases versus 40 (range 28-51) months in patients who had undergone prior hepatectomy (p = 0.09). CONCLUSION: The main parameter associated with poor outcome after lung resection of CRC metastases is a history of liver metastases

A role of 18F-fluorodeoxyglucose positron emission/computed tomography in a strategy for abdominal wall metastasis of colorectal mucinous adenocarcinoma developed after laparoscopic surgery

Metastasis to the abdominal wall including port sites after laparoscopic surgery for colorectal cancer is rare. Resection of metastatic lesions may lead to greater survival benefit if the abdominal wall metastasis is the only manifestation of recurrent disease. A 57-year-old man, who underwent laparoscopic surgery for advanced mucinous adenocarcinoma of the cecum 6 years prior, developed a nodule in the surgical wound at the lower right abdomen. Although tumor markers were within normal limits, the metastasis to the abdominal wall and abdominal cavity from the previous cecal cancer was suspected. An abdominal computed tomography scan did not provide detective evidence of metastasis. 18F-fluorodeoxyglucose positron emission/computed tomography (18F-FDG PET/CT) was therefore performed, which demonstrated increased 18F-fluorodeoxyglucose uptake (maximum standardized uptake value: 3.1) in the small abdominal wall nodule alone. Histopathological examination of the resected nodule confirmed the diagnosis of metastatic mucinous adenocarcinoma. Prognosis of intestinal mucinous adenocarcinoma is reported to be poorer than that of non-mucinous adenocarcinoma. In conclusion, this case suggests an important role of 18F-FDG PET/CT in early diagnosis and decision-making regarding therapy for recurrent disease in cases where a firm diagnosis of recurrent colorectal cancer is difficult to make