Exciton mediated one phonon resonant Raman scattering from one-dimensional systems

We use the Kramers-Heisenberg approach to derive a general expression for the resonant Raman scattering cross section from a one-dimensional (1D) system explicitly accounting for excitonic effects. The result should prove useful for analyzing the Raman resonance excitation profile lineshapes for a variety of 1D systems including carbon nanotubes and semiconductor quantum wires. We apply this formalism to a simple 1D model system to illustrate the similarities and differences between the free electron and correlated electron-hole theories.Comment: 10 pages, 6 figure

Chirality dependence of the radial breathing phonon mode density in single wall carbon nanotubes

A mass and spring model is used to calculate the phonon mode dispersion for single wall carbon nanotubes (SWNTs) of arbitrary chirality. The calculated dispersions are used to determine the chirality dependence of the radial breathing phonon mode (RBM) density. Van Hove singularities, usually discussed in the context of the single particle electronic excitation spectrum, are found in the RBM density of states with distinct qualitative differences for zig zag, armchair and chiral SWNTs. The influence the phonon mode density has on the two phonon resonant Raman scattering cross-section is discussed.Comment: 6 pages, 2 figures, submitted to Phys. Rev.

Presentations and word problem for strong semilattices of semigroups

Let I be a semilattice, and Si (i ∈ I) be a family of disjoint semigroups. Then we prove that the strong semilattice S = S[I, Si , φj,i] of semigroups Si with homomorphisms φj,i : Sj → Si (j ≥ i) is finitely presented if and only if I is finite and each Si (i ∈ I) is finitely presented. Moreover, for a finite semilattice I, S has a soluble word problem if and only if each Si (i ∈ I) has a soluble word problem. Finally, we give an example of nonautomatic semigroup which has a soluble word problem

Tunable Resonant Raman Scattering from Singly Resonant Single Wall Carbon Nanotubes

We perform tunable resonant Raman scattering on 17 semiconducting and 7 metallic singly resonant single wall carbon nanotubes. The measured scattering cross-section as a function laser energy provides information about a tube's electronic structure, the lifetime of intermediate states involved in the scattering process and also energies of zone center optical phonons. Recording the scattered Raman signal as a function of tube location in the microscope focal plane allows us to construct two-dimensional spatial maps of singly resonant tubes. We also describe a spectral nanoscale artifact we have coined the "nano-slit effect"

Distinct Mechanisms for Induction and Tolerance Regulate the Immediate Early Genes Encoding Interleukin 1β and Tumor Necrosis Factor α

Interleukin-1β and Tumor Necrosis Factor α play related, but distinct, roles in immunity and disease. Our study revealed major mechanistic distinctions in the Toll-like receptor (TLR) signaling-dependent induction for the rapidly expressed genes (IL1B and TNF) coding for these two cytokines. Prior to induction, TNF exhibited pre-bound TATA Binding Protein (TBP) and paused RNA Polymerase II (Pol II), hallmarks of poised immediate-early (IE) genes. In contrast, unstimulated IL1B displayed very low levels of both TBP and paused Pol II, requiring the lineage-specific Spi-1/PU.1 (Spi1) transcription factor as an anchor for induction-dependent interaction with two TLR-activated transcription factors, C/EBPβ and NF-κB. Activation and DNA binding of these two pre-expressed factors resulted in de novo recruitment of TBP and Pol II to IL1B in concert with a permissive state for elongation mediated by the recruitment of elongation factor P-TEFb. This Spi1-dependent mechanism for IL1B transcription, which is unique for a rapidly-induced/poised IE gene, was more dependent upon P-TEFb than was the case for the TNF gene. Furthermore, the dependence on phosphoinositide 3-kinase for P-TEFb recruitment to IL1B paralleled a greater sensitivity to the metabolic state of the cell and a lower sensitivity to the phenomenon of endotoxin tolerance than was evident for TNF. Such differences in induction mechanisms argue against the prevailing paradigm that all IE genes possess paused Pol II and may further delineate the specific roles played by each of these rapidly expressed immune modulators. © 2013 Adamik et al

Heart echinococcus cyst as an incidental finding: early detection might be life-saving

We present a 46-year-old female smoker who was admitted to the emergency department of our hospital due to cough with blood-tinged sputum for the last four days before admission. Using echocardiography and Multi-Detector Computed Tomography (MDCT) heart Echinococcosis was diagnosed. Echinococcosis is a severe health issue in some geographical regions of the world. Hydatid infection of the heart is rare and the clinical presentation is usually insidious but there is always the lethal hazard of cyst perforation. Early diagnosis and an integrated treatment strategy are crucial. The results of surgical treatment of heart echinococcosis are better than the conservative strategy only. Extraction of the cyst combined with chemotherapy peri or post operative aiming to decrease the recurrences, consists the lege artis method of encountering this medical entity. Surgical excision was performed and the patient had an uneventful recovery and follow up at six and twelve months

Effects of implantation of bone marrow cells on cytokine levels in the ischemic heart tissue. An experimental study

<p>Abstract</p> <p>Background</p> <p>In order to achieve a safe and persistent angiogenic effect, we investigated the potential of bone marrow cells implantation to enhance angiogenesis of ischemic hearts in a rat model, and also we have investigated growth factors accompanying and intermediating the angiogenesis, and the changes occurring in the levels of cytokines and their relations with angiogenesis.</p> <p>Methods</p> <p>30 adult male Wistar albino rats from the same colony were used. After anterior myocardial infarction induced by occlusion of the left anterior descending artery, they were divided into two groups (Group I and Group II). 2 × 10⁷bone marrow cells suspended in 0.1 ml phosphate-buffered saline solution and 0.1 ml phosphate-buffered saline solution were injected at six points in the infarcted area in Group I and Group II respectively. Changes in the vascular density and, vascular endothelial growth factor, vascular cell adhesion molecule and cytokine levels in the infarcted myocardium after bone marrow cells implantation were examined.</p> <p>Results</p> <p>The implantation assay showed that bone marrow cells induced angiogenesis. Light microscopic analysis of the vascular density in the ischemic area showed that, angiogenesis had been induced to higher in Group I than Group II. Levels of vascular endothelial growth factor, vascular cell adhesion molecule and the inflammatory cytokines such as interleukin-1 and tumor necrosis factor-α in Group I were significantly elevated compared with those in Group II.</p> <p>Conclusion</p> <p>Bone marrow cells implantation induced angiogenesis in a rat ischemic heart model as a result of increase of the levels of vascular endothelial growth factor, vascular cell adhesion molecule, interleukin-1, and tumor necrosis factor-α.</p