Iterative IDMA Receivers with Random and Tree Based Interleavers

In recent days, on the horizon of wireless world, newly proposed multiple access scheme known as Interleave-Division Multiple-Access (IDMA) has made its remarkable impact. Researchers all over world, are making hard marks to establish the scheme to establish its claim as potential candidate for 4th generation wireless communication systems. This paper is concerned with the performance enhancement of iterative IDMA systems under coded & uncoded environment. The performance of an interleave division multiple access (IDMA) system can be improved by the optimized power allocation techniques. Based on the optimized power allocation technique we compare the performance of coded & uncoded IDMA system with random interleaver & tree based interleaver. During the simulation, it has been observed that tree based interleaver demonstrate the similar bit error rate (BER) performance to that of random interleaver however on other fronts including bandwidth and memory requirement at transmitter and receiver ends, it outperforms the random interleavers. Keywords: Tree Based Interleaver, Random Interleaver, IDMA, linear programming, power allocation, BER

Free products of finite groups acting on regular rooted trees

Let finite number of finite groups be given. Let n be the largest order of their composition factors. We prove explicitly that the group of finite state automorphisms of rooted n-tree contains subgroups isomorphic to the free product of given groups

Tracking plasma DNA mutation dynamics in estrogen receptor positive metastatic breast cancer with dPCR-SEQ

Serial monitoring of plasma DNA mutations in estrogen receptor positive metastatic breast cancer (ER + MBC) holds promise as an early predictor of therapeutic response. Here, we developed dPCR-SEQ, a customized assay that utilizes digital PCR-based target enrichment followed by next-generation sequencing to analyze plasma DNA mutations in ESR1, PIK3CA, and TP53. We validated dPCR-SEQ in a prospective cohort of 58 patients with ER + MBC and demonstrate excellent concordance with hotspot ESR1 mutation abundance measured by conventional digital PCR. The dPCR-SEQ assay revealed ESR1, PIK3CA, and TP53 plasma ctDNA mutations in 55%, 32%, and 32% of the study patients, respectively. We also observed dynamic changes in ESR1, PIK3CA, and TP53 ctDNA mutant allele fraction (MAF) that were frequently discordant between the different genes. Thus, monitoring plasma DNA mutation dynamics using a dPCR-SEQ assay is feasible, accurate, and may be investigated as a biomarker of therapeutic response in ER + MBC

Ground-state phase diagram of the one-dimensional half-filled extended Hubbard model

We revisit the ground-state phase diagram of the one-dimensional half-filled extended Hubbard model with on-site (U) and nearest-neighbor (V) repulsive interactions. In the first half of the paper, using the weak-coupling renormalization-group approach (g-ology) including second-order corrections to the coupling constants, we show that bond-charge-density-wave (BCDW) phase exists for U \approx 2V in between charge-density-wave (CDW) and spin-density-wave (SDW) phases. We find that the umklapp scattering of parallel-spin electrons disfavors the BCDW state and leads to a bicritical point where the CDW-BCDW and SDW-BCDW continuous-transition lines merge into the CDW-SDW first-order transition line. In the second half of the paper, we investigate the phase diagram of the extended Hubbard model with either additional staggered site potential \Delta or bond alternation \delta. Although the alternating site potential \Delta strongly favors the CDW state (that is, a band insulator), the BCDW state is not destroyed completely and occupies a finite region in the phase diagram. Our result is a natural generalization of the work by Fabrizio, Gogolin, and Nersesyan [Phys. Rev. Lett. 83, 2014 (1999)], who predicted the existence of a spontaneously dimerized insulating state between a band insulator and a Mott insulator in the phase diagram of the ionic Hubbard model. The bond alternation \delta destroys the SDW state and changes it into the BCDW state (or Peierls insulating state). As a result the phase diagram of the model with \delta contains only a single critical line separating the Peierls insulator phase and the CDW phase. The addition of \Delta or \delta changes the universality class of the CDW-BCDW transition from the Gaussian transition into the Ising transition.Comment: 24 pages, 20 figures, published versio

Constants of Weitzenb\"ock derivations and invariants of unipotent transformations acting on relatively free algebras

In commutative algebra, a Weitzenb\"ock derivation is a nonzero triangular linear derivation of the polynomial algebra $K[x_1,...,x_m]$ in several variables over a field $K$ of characteristic 0. The classical theorem of Weitzenb\"ock states that the algebra of constants is finitely generated. (This algebra coincides with the algebra of invariants of a single unipotent transformation.) In this paper we study the problem of finite generation of the algebras of constants of triangular linear derivations of finitely generated (not necessarily commutative or associative) algebras over $K$ assuming that the algebras are free in some sense (in most of the cases relatively free algebras in varieties of associative or Lie algebras). In this case the algebra of constants also coincides with the algebra of invariants of some unipotent transformation. \par The main results are the following: 1. We show that the subalgebra of constants of a factor algebra can be lifted to the subalgebra of constants. 2. For all varieties of associative algebras which are not nilpotent in Lie sense the subalgebras of constants of the relatively free algebras of rank $\geq 2$ are not finitely generated. 3. We describe the generators of the subalgebra of constants for all factor algebras $K/I$ modulo a $GL_2(K)$-invariant ideal $I$. 4. Applying known results from commutative algebra, we construct classes of automorphisms of the algebra generated by two generic $2\times 2$ matrices. We obtain also some partial results on relatively free Lie algebras.Comment: 31 page

Inflammatory breast cancer: dynamic contrast-enhanced MR in patients receiving bevacizumab. Initial experience

To retrospectively compare three dynamic contrast material-enhanced magnetic resonance (MR) imaging (dynamic MR imaging) analytic methods to determine the parameter or combination of parameters most strongly associated with changes in tumor microvasculature during treatment with bevacizumab alone and bevacizumab plus chemotherapy in patients with inflammatory or locally advanced breast cancer. MATERIALS AND METHODS: This study was conducted in accordance with the institutional review board of the National Cancer Institute and was compliant with the Privacy Act of 1974. Informed consent was obtained from all patients. Patients with inflammatory or locally advanced breast cancer were treated with one cycle of bevacizumab alone (cycle 1) followed by six cycles of combination bevacizumab and chemotherapy (cycles 2-7). Serial dynamic MR images were obtained, and the kinetic parameters measured by using three dynamic analytic MR methods (heuristic, Brix, and general kinetic models) and two region-of-interest strategies were compared by using two-sided statistical tests. A P value of .01 was required for significance. RESULTS: In 19 patients, with use of a whole-tumor region of interest, the authors observed a significant decrease in the median values of three parameters measured from baseline to cycle 1: forward transfer rate constant (Ktrans) (-34% relative change, P=.003), backflow compartmental rate constant extravascular and extracellular to plasma (Kep) (-15% relative change, P<.001), and integrated area under the gadolinium concentration curve (IAUGC) at 180 seconds (-23% relative change, P=.009). A trend toward differences in the heuristic slope of the washout curve between responders and nonresponders to therapy was observed after cycle 1 (bevacizumab alone, P=.02). The median relative change in slope of the wash-in curve from baseline to cycle 4 was significantly different between responders and nonresponders (P=.009). CONCLUSION: The dynamic contrast-enhanced MR parameters Ktrans, Kep, and IAUGC at 180 seconds appear to have the strongest association with early physiologic response to bevacizumab. Clinical trial registration no. NCT0001654

Single Spin Asymmetry ANA_N in Polarized Proton-Proton Elastic Scattering at s=200\sqrt{s}=200 GeV

We report a high precision measurement of the transverse single spin asymmetry $A_N$ at the center of mass energy $\sqrt{s}=200$ GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The $A_N$ was measured in the four-momentum transfer squared $t$ range $0.003 \leqslant |t| \leqslant 0.035$ \GeVcSq, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of $A_N$ and its $t$-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this $\sqrt{s}$, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure