Finiteness of fixed equilibrium configurations of point vortices in the plane with a background flow

For a dynamic system consisting of n point vortices in an ideal plane fluid with a steady, incompressible and irrotational background flow, a more physically significant definition of a fixed equilibrium configuration is suggested. Under this new definition, if the complex polynomial w that determines the aforesaid background flow is non-constant, we have found an attainable generic upper bound $\frac{(m+n-1)!}{(m-1)!\,n_1!\cdots n_{i_0}!}$ for the number of fixed equilibrium configurations. Here, m = deg w, i0 is the number of species, and each ni is the number of vortices in a species. We transform the rational function system arising from fixed equilibria into a polynomial system, whose form is good enough to apply the BKK theory (named after Bernshtein (1975 Funct. Anal. Appl. 9 183–5), Khovanskii (1978 Funct. Anal. Appl. 12 38–46) and Kushnirenko (1976 Funct. Anal. Appl. 10 233–5)) to show the finiteness of its number of solutions. Having this finiteness, the required bound follows from Bézout's theorem or the BKK root count by Li and Wang (1996 Math. Comput. 65 1477–84).postprin

Higher-Order, Polar and Sz.-Nagy’s Generalized Derivatives of Random Polynomials with Independent and Identically Distributed Zeros on the Unit Circle

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Single-breathhold myocardial T2 and T2* quantification in normal volunteer subjects at 3T

Myocardial Tissue Characterization: Fat, Hemorrhage & Edema - Poster presentationIncreased B0 and B1 inhomogeneity, together with increased motion artifacts, present challenges for cardiac imaging and quantitation at 3T. This study measured myocardial T2 in normal subjects at 3T using a novel single-breathhold black-blood hybrid TSE/MESE T2 measurement protocol. The average myocardial T2 was found to be 39.6±7.4ms, with peak-to-peak variations of the measured T2 values < 5%. The results demonstrate the feasibility of myocardial T2 quantitation at 3T.published_or_final_versionThe 17th Scientific Meeting & Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM), Honolulu, HI., 18-24 April 2009. In Proceedings of ISMRM 17th Scientific Meeting & Exhibition, 2009, p. 375

Multiparametric magnetic resonance imaging of normal and degenerative lumbar intervertebral discs

Magnetic resonance imaging (MRI) has been shown to improve the diagnosis and management of patients with intervertebral disc (IVD) related disorders. Multiparametric MRI offers the possibility of noninvasively assessing multiple aspects of pathophysiological processes that exist simultaneously, thereby further assisting in patient treatment management. The purpose of this study is to determine the correlation between relaxation parameters (T1ρ and T2), diffusion properties including fractional anisotropy (FA) and mean diffusivity (MD) measured by diffusion tensor imaging (DTI) and various clinical findings in human IVD. Our results suggest that each parameter may attribute different sensitivity to tissue properties.postprin

Ultrashort time-to-echo MRI of the cartilagenous endplate and relationship to degenerative disc disease and schmorl's nodes

Session - The Short of ItINTRODUCTION: The vertebral endplate is composed of an inner bony and outer cartilaginous endplates (CEP). The CEP supplies the intervertebral disc (IVD) with nutrients and metabolites, and is instrumental for metabolism, exchange of waste products and biomechanics of the disc 1. Lumbar disc degeneration on MRI is a risk factor for the development of low back pain 2. It has been previously hypothesized that changes in disc mechanics may be initiated by damage to the endplate 3, 4. Similarly, CEP defects may be involved in the formation of Schmorl’s nodes (SNs) (i.e. invagination of IVD material into the adjacent endplates) 5, which associated with severity of lumbar disc degeneration 6. The ultrashort time-to-echo (UTE) MRI is an imaging technique that enables improved visualization of tissues with short T2 relaxation that appear dark in signal on conventional T2-weighted (T2W) imaging. By employing this technique in the lumbar spine, we believe that the CEP, which appears hypointense in T2W MRI, may be observed as continuous high-signal and may thus be differentiated from the bony endplate. Although cadaveric studies have addressed the feasibility of UTE in assessing the CEP 7, studies addressing such technology in live human subjects …published_or_final_versionThe 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011), Montreal, QC., 7-13 May 2011. In Proceedings of the 19th ISMRM, 2011, v. 19, p. 57

Ultrashort time-to-echo MRI of the cartilagenous endplate & relationship to degenerative disc disease & Schmorl’s nodes

Session - The Short of It: no. 570Early diagnosis of CEP defects by UTE technique may provide useful information for understanding the pathogenesis of each of DDD and Schmorl¡¦s nodes (SN). The objective of this study was to assess CEP integrity in normal IVD levels, levels with degenerated IVDs and levels with SNs. Based on the UTE images, CEP defects were defined as discontinuity of high signal over 4 consecutive slices. Results showed that CEP defects were found to have a 4.5 fold increased likelihood of having DDD. No association between CEP defects and SNs was established. The effects of age and CEP defects were found to be level dependent. (abstract by publisher)postprin

Axial and radial diffusivities as potential markers for characterization of white matter lesions and predicting lesion outcome in a neonatal rat hypoxia-ischemia model

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Inhibition of class I histone deacetylases by romidepsin potently induces Epstein-Barr virus lytic cycle and mediates enhanced cell death with ganciclovir

Pan-histone deacetylase (HDAC) inhibitors, which inhibit 11 HDAC isoforms, are widely used to induce Epstein-Barr virus (EBV) lytic cycle in EBV-associated cancers in vitro and in clinical trials. Here, we hypothesized that inhibition of one or several specific HDAC isoforms by selective HDAC inhibitors could potently induce EBV lytic cycle in EBV-associated malignancies such as nasopharyngeal carcinoma (NPC) and gastric carcinoma (GC). We found that inhibition of class I HDACs, particularly HDAC-1, -2 and -3, was sufficient to induce EBV lytic cycle in NPC and GC cells in vitro and in vivo. Among a panel of selective HDAC inhibitors, the FDA-approved HDAC inhibitor romidepsin was found to be the most potent lytic inducer, which could activate EBV lytic cycle at ∼0.5 to 5 nM (versus ∼800 nM achievable concentration in patients' plasma) in more than 75% of cells. Upregulation of p21WAF1 , which is negatively regulated by class I HDACs, was observed before the induction of EBV lytic cycle. The upregulation of p21WAF1 and induction of lytic cycle were abrogated by a specific inhibitor of PKC-δ but not the inhibitors of PI3K, MEK, p38 MAPK, JNK or ATM pathways. Interestingly, inhibition of HDAC-1, -2 and -3 by romidepsin or shRNA knockdown could confer susceptibility of EBV-positive epithelial cells to the treatment with ganciclovir (GCV). In conclusion, we demonstrated that inhibition of class I HDACs by romidepsin could potently induce EBV lytic cycle and mediate enhanced cell death with GCV, suggesting potential application of romidepsin for the treatment of EBV-associated cancers.postprin

Molecular Characterization of an Atypical IncX3 Plasmid pKPC-NY79 Carrying blaKPC-2 in a Klebsiella pneumoniae

The IncX family of plasmids has recently been expanded to include at least four subtypes, IncX1-IncX4. The revised classification provides an opportunity for improving our understanding of the sequence diversity of the IncX plasmids and the resistance genes they carried. We described the complete nucleotide sequence of a novel IncX3 plasmid, pKPC-NY79 (42,447 bp) from a sequence-type 258 Klebsiella pneumoniae strain that was isolated from a patient who was hospitalized in New York, United States. In pKPC-NY79, the plasmid scaffold and genetic load region were highly similar to homologous regions in pIncX-SHV (IncX3, JN247852) and the bla KPC carrying pKpQIL (IncFII k, GU595196), respectively, indicating that it has possibly arisen through recombination of plasmids. The bla KPC-2 gene, as part of a transposon Tn4401a, was found within the genetic load region. The backbone of pKPC-NY79 differs from pIncX-SHV by a deletion involving the gene tandem hns-topB (encoding H-NS protein and topoisomerase III, respectively) and a putative ATPase gene. Unexpectedly, the impact of the hns-topB deletion on host fitness and plasmid stability was found to be small. In conclusion, the findings contribute to a better understanding of the plasmid platforms carrying bla KPC and of variations in the backbone of the IncX3 plasmids. © 2013 Springer Science+Business Media New York.postprin