Bhatnagar M.R.,Indian Institute of Technology Delhi |
Hjorungnes A.,University Graduate Center
IEEE Transactions on Wireless Communications | Year: 2011
Decode-and-forward (DF) protocol based cooperative communication is vulnerable to the erroneous relaying by the relay. In this paper, we derive a maximum-likelihood (ML) decoder for the DF protocol utilizing arbitrary complex-valued constellations including M-PSK, M-PAM, and M-QAM. A set-up of a single pair of source and destination with one relay is studied. The source and the relay utilize orthogonal uncoded transmissions. The relay performs ML decoding and forwards the decoded symbol to the destination, and it might commit errors in decoding the data. The ML decoder at the destination is obtained by maximizing the probability density function (p.d.f.) of the data received during two orthogonal transmissions at the destination under the assumption that the average probability of error of the source-relay link is known at the destination. The proposed ML decoder is a generalized decoder which is applicable to arbitrary constellations, whereas, one existing DF cooperative decoder is applicable to the real valued constellations like BPSK and M-PAM. One existing decoder is also applicable to M 2-QAM constellations. We also derive a low-complexity piecewise linear (PL) decoder for arbitrary complex-valued M-point constellations which performs similar to the ML decoder for all signal-to-noise ratio values. An approximate expression of the symbol error rate (SER) of the PL decoder for M-PSK constellation is derived. By using the approximate SER expressions, it is proved that the proposed ML and PL decoders achieve full diversity of two in the cooperative system studied. © 2011 IEEE.
Tzoneva G.,University Graduate Center |
Ferrando A.A.,Columbia University
Current Topics in Microbiology and Immunology | Year: 2012
NOTCH1 receptor signaling plays a central role in T-cell lineage specification and in supporting the growth and proliferation of immature T-cell progenitors in the thymus during lymphoid development. In T-cell acute lymphoblastic leukemia (T-ALL), a tumor resulting from the malignant transformation of T-cell progenitors, aberrant and constitutively active NOTCH1 signaling triggered by activating mutations in the NOTCH1 gene contributes to oncogenic transformation and is a hallmark of this disease. Most notably, small molecule γ-secretase inhibitors (GSIs) can effectively block NOTCH1 signaling in T-ALL, and could be exploited as a targeted therapy in this disease. In addition, a number of emerging anti-NOTCH therapeutic strategies including anti-NOTCH1 inhibitory antibodies, small peptide inhibitors of NOTCH signaling and combination therapies with GSIs and glucocorticoids, have recently been proposed. Finally, the identification of NOTCH1 mutations in solid tumors and chronic lymphocytic leukemias has increased even further the clinical relevance of NOTCH signaling as a therapeutic target in human cancer. Here we review our current understanding of NOTCH1-induced transformation, the mechanisms of action of oncogenic NOTCH1 in T-ALL and the therapeutic and prognostic implications of NOTCH1 mutations in T-ALL. © 2012 Springer-Verlag Berlin Heidelberg.
Ulversoy T.,University Graduate Center
IEEE Communications Surveys and Tutorials | Year: 2010
Software Defined Radio (SDR) may provide flexible, upgradeable and longer lifetime radio equipment for the military and for civilian wireless communications infrastructure. SDR may also provide more flexible and possibly cheaper multi-standard-terminals for end users. It is also important as a convenient base technology for the future context-sensitive, adaptive and learning radio units referred to as cognitive radios. SDR also poses many challenges, however, some of them causing SDR to evolve slower than otherwise anticipated. Transceiver development challenges include size, weight and power issues such as the required computing capacity, but also SW architectural challenges such as waveform application portability. SDR has demanding implications for regulators, security organizations and business developers. © 2010 IEEE.
Sasirekha B.,University Graduate Center
EXCLI Journal | Year: 2013
Urinary tract infections (UTIs) are one of the most common bacterial infections in humans. Current knowledge on antimicrobial susceptibility pattern is essential for appropriate therapy. Therefore the aim of the present study was to determine the distribution and antibiotic susceptibility pattern of bacterial strains, with special reference to ESBL, AmpC β-lactamase and MRSA production. A total of 325 clinical isolates were collected from UTI patients from various tertiary care hospitals over a period of 6 months (June 2011 to December 2011). The antimicrobial susceptibility to various drugs was studied by the disc diffusion method as guided by CLSI guidelines. Confirmation of the extended spectrum β-lactamase (ESBL), AmpC β- lactamase and methicillin resistant Staphylococcus aureus (MRSA) production was done by an E-test respectively. Of the 325 isolates, 225 were characterized as gram negative and 77 isolates as S. aureus isolates. The majority (69.3 %) of the isolates were from females compared to males (30.7 %). Prevalence of ESBL and AmpC β-lactamase and the coexistence of the phenotype (ESBL+ AmpC β-lactamase) and MRSA in the urinary isolates were found to be 48.9 %, 20.4 %, 6.2 % and 27.5 % respectively. Ampicillin/sulbactam, norfloxacin should be no longer considered as first line of drugs for UTI, because of high resistance. Parentral drugs such as aminoglycosides, carbapenems and piperacillin/tazobactum can be the alternative choice for complicated UTI. Also, control measures such as judicious use of antibiotics, formulation of infection committee may control the spread of resistance.
Lawrence P.M.,Stony Brook University Medical Center |
Lawrence P.M.,University Graduate Center |
Studholme K.M.,Stony Brook University Medical Center
Journal of Comparative Neurology | Year: 2014
The laboratory mouse is increasingly a subject for visual system investigation, but there has been no comprehensive evaluation of this species' visual projections. Here, projections were visualized and mapped following intraocular injection of cholera toxin B subunit. Tissue was processed using standard procedures applied to 30 μm free-floating sections with diaminobenzidine as the chromogen. The mouse retina projects to ~46 brain regions, including 14 not previously described in this species. These include two amygdaloid nuclei, the horizontal limb of the diagonal band, the paraventricular hypothalamic nucleus, several visual thalamic nuclei, the paranigral nucleus, several pretectal nuclei, and the dorsal cortex of the inferior colliculus. Dense retinal patches were also observed in a narrow portion of the ipsilateral intermediate layer of the superior colliculus. The superior fasciculus of the accessory optic tract, which innervates the medial terminal nucleus, was also determined to be a terminal zone throughout its length. The results are compared with previous descriptions of projections from mouse intrinsically photoreceptive retinal ganglion cells, and with data from the hamster, Nile grass rat, and laboratory rat. The retinal projection patterns are similar in all four species, although there are many differences with respect to the details. The specific visual functions of most retinorecipient areas are unknown, but there is substantial convergence of retinal projections onto regions concerned with olfaction and audition. J. Comp. Neurol. 522:3733-3753, 2014. © 2014 Wiley Periodicals, Inc.