New approaches for the design of low-complexity radix-based FFT and FHT algorithms

The discrete Fourier transform (DFT) and discrete Hartley transform (DHT) play a crucial role in one- and multi-dimensional digital signal processing applications. Traditionally, the main concern in the design of fast Fourier transform (FFT) and fast Hartley transform (FHT) algorithms has been the reduction of the arithmetic complexity. However, with the recent advances in the digital technology and the present demands of such transforms in low-power high-performance real-time applications, a more comprehensive treatment of the computational and structural complexities must be considered in the design of the algorithms. The objective of this thesis is to design one- and multi-dimensional FFT and FHT algorithms that address the problem of reducing the number of arithmetic operations, data transfers, address generations, and twiddle factor evaluations or accesses to the lookup table, while possessing features such as simplicity, regularity, modularity, easy indexing scheme, and butterfly-style and in-place computations that are highly desirable characteristics for software or hardware implementations of the algorithms. To achieve these objectives, radix-based algorithms are proposed by introducing new decomposition strategies, efficient index mappings, and by an appropriate use of the Kronecker product. A general decomposition method, which is based on the radix-2 approach, valid for any dimension and applicable to both the DHT and DFT, and which significantly reduces the complexity of the FHT algorithms, is proposed. This method enables us to develop multidimensional FHT and FFT algorithms. A new approach for computing the DFT and DHT using a unified structure is proposed by establishing a close relationship, valid for any dimension, between the radix-2 based FHT and FFT algorithms. An efficient method, based on the radix-2 approach, for pruning output samples of a 1-D or 2-D DFT is proposed by grouping in its 1-D or 2-D FFT algorithm all the stages that involve unnecessary operations into a single stage and by introducing a new recursive technique for the computations required in the resulting stage. A technique is presented to improve the performance of the radix-4, radix-8 and radix-16 FFT algorithms in terms of the number of twiddle factor evaluations or accesses to the lookup table without any increase in the computational or structural complexities of the algorithms. In order to take advantage of the lowest structural complexity provided by the radix-2 approach and reduced computational complexity offered by the radix-4 approach, a technique suitable for combining these two approaches is introduced in order to develop efficient 3-D FFT and FHT algorithms. A radix-2/8 approach for reducing the complexity in the computation of the 1-D DFT and DHT of lengths N = q {604} 2 m is proposed by appropriately mixing the radix-2 and radix-8 index maps. This approach is extended to 2-D and 3-D DFTs. It is shown that the proposed radix-2/8 approach is superior to all the other existing radix-based approaches in providing low-complexity 1-D, 2-D and 3-D FFT, and 1-D FHT algorithms

The oxysterol 27-hydroxycholesterol increases β-amyloid and oxidative stress in retinal pigment epithelial cells

<p>Abstract</p> <p>Background</p> <p>Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological features including β-amyloid (Aβ) peptide accumulation, oxidative damage, and cell death. The causes of AD and AMD are not known but several studies suggest disturbances in cholesterol metabolism as a culprit of these diseases. We have recently shown that the cholesterol oxidation metabolite 27-hydroxycholesterol (27-OHC) causes AD-like pathology in human neuroblastoma SH-SY5Y cells and in organotypic hippocampal slices. However, the extent to which and the mechanisms by which 27-OHC may also cause pathological hallmarks related to AMD are ill-defined. In this study, the effects of 27-OHC on AMD-related pathology were determined in ARPE-19 cells. These cells have structural and functional properties relevant to retinal pigmented epithelial cells, a target in the course of AMD.</p> <p>Methods</p> <p>ARPE-19 cells were treated with 0, 10 or 25 μM 27-OHC for 24 hours. Levels of Aβ peptide, mitochondrial and endoplasmic reticulum (ER) stress markers, Ca²⁺homeostasis, glutathione depletion, reactive oxygen species (ROS) generation, inflammation and cell death were assessed using ELISA, Western blot, immunocytochemistry, and specific assays.</p> <p>Results</p> <p>27-OHC dose-dependently increased Aβ peptide production, increased levels of ER stress specific markers caspase 12 and gadd153 (also called CHOP), reduced mitochondrial membrane potential, triggered Ca²⁺dyshomeostasis, increased levels of the nuclear factor κB (NFκB) and heme-oxygenase 1 (HO-1), two proteins activated by oxidative stress. Additionally, 27-OHC caused glutathione depletion, ROS generation, inflammation and apoptotic-mediated cell death.</p> <p>Conclusions</p> <p>The cholesterol metabolite 27-OHC is toxic to RPE cells. The deleterious effects of this oxysterol ranged from Aβ accumulation to oxidative cell damage. Our results suggest that high levels of 27-OHC may represent a common pathogenic factor for both AMD and AD.</p

Diagnosed a Patient with Central Serous Chorioretinopathy? Now What?: Management of Central Serous Chorioretinopathy

The goal of this paper is to provide a comprehensive review of the management options for central serous chorioretinopathy (CSCR). The majority of cases of acute CSCR may be managed with observation and cessation of corticosteroids, if possible, as well as life-style modifications including stress reduction and control of hypertension. The management of chronic disease is more challenging and may include either medication or laser-based treatment. Management of CSCR necessitates an individualized and selective treatment approach. There is overall poor evidence for the use of systemic and intravitreal medications. From this class of treatments, mineralocorticoid receptor antagonists appear to have the greatest potential. Although conventional thermal photocoagulation may be used in select cases, the most promising treatment options at this time for chronic CSCR are photodynamic therapy, either half-dose or half-fluence, and non-damaging (subthreshold) retinal laser therapy

Salinomycin inhibits prostate cancer growth and migration via induction of oxidative stress

BACKGROUND: We have shown that a sodium ionophore monensin inhibits prostate cancer cell growth. A structurally related compound to monensin, salinomycin, was recently identified as a putative cancer stem cell inhibitor. METHODS: The growth inhibitory potential of salinomycin was studied in a panel of prostate cells. To get insights into the mechanism of action, a variety of assays such as gene expression and steroid profiling were performed in salinomycin-exposed prostate cancer cells. RESULTS: Salinomycin inhibited the growth of prostate cancer cells, but did not affect non-malignant prostate epithelial cells. Salinomycin impacted on prostate cancer stem cell functions as evidenced by reduced aldehyde dehydrogenase activity and the fraction of CD44(+) cells. Moreover, salinomycin reduced the expression of MYC, AR and ERG, induced oxidative stress as well as inhibited nuclear factor-κB activity and cell migration. Furthermore, profiling steroid metabolites revealed increased levels of oxidative stress-inducing steroids 7-ketocholesterol and aldosterone and decreased levels of antioxidative steroids progesterone and pregnenolone in salinomycin-exposed prostate cancer cells. CONCLUSION: Our results indicate that salinomycin inhibits prostate cancer cell growth and migration by reducing the expression of key prostate cancer oncogenes, inducing oxidative stress, decreasing the antioxidative capacity and cancer stem cell fraction

Optimization approaches for civil applications of unmanned aerial vehicles (UAVs) or aerial drones: A survey

Unmanned aerial vehicles (UAVs), or aerial drones, are an emerging technology with significant market potential. UAVs may lead to substantial cost savings in, for instance, monitoring of difficult-to-access infrastructure, spraying fields and performing surveillance in precision agriculture, as well as in deliveries of packages. In some applications, like disaster management, transport of medical supplies, or environmental monitoring, aerial drones may even help save lives. In this article, we provide a literature survey on optimization approaches to civil applications of UAVs. Our goal is to provide a fast point of entry into the topic for interested researchers and operations planning specialists. We describe the most promising aerial drone applications and outline characteristics of aerial drones relevant to operations planning. In this review of more than 200 articles, we provide insights into widespread and emerging modeling approaches. We conclude by suggesting promising directions for future research