Representation theory for high-rate multiple-antenna code design

Multiple antennas can greatly increase the data rate and reliability of a wireless communication link in a fading environment, but the practical success of using multiple antennas depends crucially on our ability to design high-rate space-time constellations with low encoding and decoding complexity. It has been shown that full transmitter diversity, where the constellation is a set of unitary matrices whose differences have nonzero determinant, is a desirable property for good performance. We use the powerful theory of fixed-point-free groups and their representations to design high-rate constellations with full diversity. Furthermore, we thereby classify all full-diversity constellations that form a group, for all rates and numbers of transmitter antennas. The group structure makes the constellations especially suitable for differential modulation and low-complexity decoding algorithms. The classification also reveals that the number of different group structures with full diversity is very limited when the number of transmitter antennas is large and odd. We, therefore, also consider extensions of the constellation designs to nongroups. We conclude by showing that many of our designed constellations perform excellently on both simulated and real wireless channels

Apoptosis/necrosis induction by ultraviolet, in ER positive and ER negative breast cancer cell lines

Background: Ultraviolet (UV) light exposure has been one of the major inducers of apoptosis. UV exposure has caused pyrimidine dimers and DNA fragmentation which might lead to cell cycle arrest and apoptosis signals activation. UV induced apoptosis has investigated in MDA-MB 468 as an ER negative breast adenocarcinoma and MCF-7 as an ER positive breast cancer cell line. Apoptosis induction rate by UV might be different in these two types of cells due to different biological characteristics of the cell. Objectives: In this paper we have evaluated serial dose of UV-B exposure on ER positive and ER negative breast cancer cell lines and its effect on apoptosis or necrosis induction in these cells. Materials and Methods: MDA-MB468 and MCF-7 cell lines have cultured for 24 hours and UV exposure has carried out at 290 nm at dose of 154 J/m2 to 18 KJ/m2 using UV lamp. UV exposed cells have incubated in cell culture condition for 24 or 48 hours following UV exposure and the cells have stained and analyzed by flow cytometry for apoptosis evaluation by Annexin V/PI method. Results: Apoptosis rate (PI and Annexin V double positive cells) after 24 hours incubation was higher in 24 hours in comparison with 48 hours incubation in both cell lines. The frequency of PI positive MDA-MB 468 cells was higher than PI and Annexin V double positive cells after 48 hours. PI positive MDA-MB 468 cells were significantly higher than MCF-7 cells in 24 hours incubation time. Conclusions: The results have shown that MDA-MB 468 cells were more sensitive to UV exposure and DNA fragmentation and necrosis pathway was dominant in these cells. © 2015, Iranian Journal of Cancer Prevention

Comparison of the effect of cycloplegic versus NSAID eye drops on pain after photorefractive keratectomy

Purpose: To compare the effect of Homatropine and Diclofenac eye drops for reducing pain after photorefractive keratectomy (PRK). Methods: This randomized, double-masked, interventional study included 32 patients (64 eyes) who underwent bilateral PRK. After operation, patients received Homatropine eye drops in one eye and Diclofenac eye drops in the fellow eye for 48 h. The level of pain was evaluated using visual analogue scale (VAS), verbal rating scale (VRS), and pain rating index (PRI) at 0.5, 24, and 48 h after operation. Results: The level of pain was statistically similar between the two eyes half an hour after operation; however, Diclofenac eyes had significantly less pain 24 h after operation (1.7 ± 1.4 vs 5.8 ± 2.1, P < 0.001 for VAS, 0.6 ± 0.6 vs 2.4 ± 1.1, P < 0.001 for VRS, and 3.4 ± 3.4 vs 12.0 ± 6.9, P < 0.001 for PRI, respectively). Also, 48 h after surgery, the pain scores were less in the Diclofenac eyes (1.6 ± 1.8 vs 3.4 ± 2.8, P < 0.001 for VAS, 0.6 ± 0.6 vs 1.2 ± 0.9, P < 0.001 for VRS, and 3.3 ± 3.7 vs 6.5 ± 6.2, P < 0.001 for PRI). No case with delayed epithelial healing in both groups was observed. Conclusion: The effect of Homatropine seems to be lower compared to Diclofenac for reducing pain after photorefractive keratectomy. © 2015 Iranian Society of Ophthalmology

Long Distance Continuous-Variable Quantum Key Distribution with a Gaussian Modulation

We designed high-efficiency error correcting codes allowing to extract an errorless secret key in a continuous-variable quantum key distribution protocol using a Gaussian modulation of coherent states and a homodyne detection. These codes are available for a wide range of signal-to-noise ratios on an AWGN channel with a binary modulation and can be combined with a multidimensional reconciliation method proven secure against arbitrary collective attacks. This improved reconciliation procedure considerably extends the secure range of a continuous-variable quantum key distribution with a Gaussian modulation, giving a secret key rate of about 10^{-3} bit per pulse at a distance of 120 km for reasonable physical parameters.Comment: 8 pages, 5 figures, 5 table

Statistical Mechanics Analysis of LDPC Coding in MIMO Gaussian Channels

Using analytical methods of statistical mechanics, we analyse the typical behaviour of a multiple-input multiple-output (MIMO) Gaussian channel with binary inputs under LDPC network coding and joint decoding. The saddle point equations for the replica symmetric solution are found in particular realizations of this channel, including a small and large number of transmitters and receivers. In particular, we examine the cases of a single transmitter, a single receiver and the symmetric and asymmetric interference channels. Both dynamical and thermodynamical transitions from the ferromagnetic solution of perfect decoding to a non-ferromagnetic solution are identified for the cases considered, marking the practical and theoretical limits of the system under the current coding scheme. Numerical results are provided, showing the typical level of improvement/deterioration achieved with respect to the single transmitter/receiver result, for the various cases.Comment: 25 pages, 7 figure

Cytomegalovirus and toxoplasma gondii: Common causes of profound sensori neural hearing loss in children with cochlear implant surgery in a highly immune population: Tehran; Iran

Background: Iranian population is highly immune from T.Gondii and CMV infection. Objective: To determine the immunity to T.Gondii and CMV in children with the cochlear implant surgery accompanied with the profound Idiopathic type of SNHL Methods and Materials: We studied 45 cases with the cochlear implant surgery (Idiopathic profound SNHL) and 30 controls with the normal OAEs in a cross-sectional study in Rasoul Akram Hospital in Tehran (2010-2012). Blood samples (2 ml) were centrifuged and were kept frozen at-20°C. Sera searched for the specific antibodies against CMV and T.Gondii. The enzyme-linked immunosorbent assay (ELISA; BioChem Immune System) was calculated qualitatively. (P value< 0.05) Results: Range of age in cases with profound SNHL (<95 dB) was 6 months-to-14 years; mean=3.4+3.16 y; Idiopathic type of SNHL children diagnosed in 45 cases were younger than cases with non-Idiopathic SNHL (mean age=20 months; PV=0.05). Positive T.Gondii-IgM was found in 8 /45 (17.7) and also one of these cases (2.2) had positive T.Gondii �IgG test. Positive CMV-IgM & IgG were determined in 23 and 51 of cases, respectively. Positive T.Gondii �IgG was observed in 60 (18/30) of controls but none of them had positive T.Gondii � IgM. Positive CMV-IgM & IgG in controls was 3.3 and 90, respectively. Conclusion: CMV infection is one of the most common infections found in profound idiopathic SNHL children especially in younger cases (< 2 years) even in highly immune Iranian populations. Probably, T.Gondii infection has a relative role in younger cases with profound SNHL but a higher role in mild to moderate SNHL in our pediatric population. Most of the T.Gondii infected SNHL cases never require cochlear implant surgery. In future, a cohort study for prenatal diagnosis of the intrauterine infection and the role of infection in producing SNHLwould be very helpful. It has been recommended to search the specific antibodies against these two common infections in all types of SNHL in pediatric groups which are treatable especially in younger cases (<2 year). © 2019 Noorbakhsh et al

Peer-to-peer live video streaming with rateless codes for massively multiplayer online games

International audienc

On encoding symbol degrees of array BP-XOR codes

Low density parity check (LDPC) codes, LT codes and digital fountain techniques have received significant attention from both academics and industry in the past few years. By employing the underlying ideas of efficient Belief Propagation (BP) decoding process (also called iterative message passing decoding process) on binary erasure channels (BEC) in LDPC codes, Wang has recently introduced the concept of array BP-XOR codes and showed the necessary and sufficient conditions for MDS [k + 2,k] and [n,2] array BP-XOR codes. In this paper, we analyze the encoding symbol degree requirements for array BP-XOR codes and present new necessary conditions for array BP-XOR codes. These new necessary conditions are used as a guideline for constructing several array BP-XOR codes and for presenting a complete characterization (necessary and sufficient conditions) of degree two array BP-XOR codes and for designing new edge-colored graphs. Meanwhile, these new necessary conditions are used to show that the codes by Feng, Deng, Bao, and Shen in IEEE Transactions on Computers are incorrect