Improving data prefetching efficacy in multimedia applications

The workload of multimedia applications has a strong impact on cache memory performance, since the locality of memory references embedded in multimedia programs differs from that of traditional programs. In many cases, standard cache memory organization achieves poorer performance when used for multimedia. A widely-explored approach to improve cache performance is hardware prefetching, which allows the pre-loading of data in the cache before they are referenced. However, existing hardware prefetching approaches are unable to exploit the potential improvement in performance, since they are not tailored to multimedia locality. In this paper we propose novel effective approaches to hardware prefetching to be used in image processing programs for multimedia. Experimental results are reported for a suite of multimedia image processing programs including MPEG-2 decoding and encoding, convolution, thresholding, and edge chain coding

The vector-gradient Hough transform

The paper presents a new transform, called vector-gradient Hough transform, for identifying elongated shapes in gray-scale images. This goal is achieved not only by collecting information on the edges of the objects, but also by reconstructing their transversal profile of luminosity. The main features of the new approach are related to its vector space formulation and the associated capability of exploiting all the vector information of the luminosity gradien

Neighbor cache prefetching for multimedia image and video processing

Cache performance is strongly influenced by the type of locality embodied in programs. In particular, multimedia programs handling images and videos are characterized by a bidimensional spatial locality, which is not adequately exploited by standard caches. In this paper we propose novel cache prefetching techniques for image data, called neighbor prefetching, able to improve exploitation of bidimensional spatial locality. A performance comparison is provided against other assessed prefetching techniques on a multimedia workload (with MPEG-2 and MPEG-4 decoding, image processing, and visual object segmentation), including a detailed evaluation of both the miss rate and the memory access time. Results prove that neighbor prefetching achieves a significant reduction in the time due to delayed memory cycles (more than 97% on MPEG-4 with respect to 75% of the second performing technique). This reduction leads to a substantial speedup on the overall memory access time (up to 140% for MPEG-4). Performance has been measured with the PRIMA trace-driven simulator, specifically devised to support cache prefetching

Krill oil, vitamin D and Lactobacillus reuteri cooperate to reduce gut inflammation

Current research into original therapies to treat intestinal inflammation is focusing on no-drug therapies. KLD is a mixture of krill oil (KO), probiotic Lactobacillus reuteri (LR), and vitamin D (VitD3). The aim of this study was to assess in vitro and in vivo the potential cooperative effects of KLD in reducing gut inflammation. Colorectal adenocarcinoma cell lines, CACO2 and HT29, and C57BL/6 mice were used for in vitro and in vivo analyses, respectively. Cells were exposed to cytomix (interferon gamma + tumour necrosis factor alpha (TNF-a)) to induce inflammation or co-exposed to cytomix and KO, LR and VitD3 alone or to cytomix and KLD. Animals were treated for 7 days with dextran sodium sulphate (DSS) to induce colitis or with DSS and KLD. In vitro assays: F-actin expression was analysed by immunofluorescence; scratch test and trans-epithelial electric resistance test were performed to measure wound healing; adhesion/invasion assays of adhesive and invasive Escherichia coli (AIEC) bacteria were made; mRNA expression of TNF-α, interleukin (IL)-8 and vitamin D receptor (VDR) was detected by quantitative PCR. In vivo assays: body weight, clinical score, histological score and large intestine weight and length were estimated; mRNA expression of TNF-α, IL-1ß, IL-6, IL-10 by quantitative PCR; VDR expression was detected by quantitative PCR and immunohistochemistry. In vitro: KLD restores epithelial cell-cell adhesion and mucosal healing during inflammation, while decreases the adhesiveness and invasiveness of AIEC bacteria and TNF-α and IL-8 mRNA expression and increases VDR expression. In vivo: KLD significantly improves body weight, clinical score, histological score and large intestine length of mice with DSS-induced colitis and reduces TNF-α, IL-1ß and IL-6 mRNA levels, while increases IL-10 mRNA and VDR levels. KLD has significant effects on the intestinal mucosa, strongly decreasing inflammation, increasing epithelial restitution and reducing pathogenicity of harmful commensal bacteria

Performance analysis of MPEG-4 decoder and encoder

© 2002 Croatian Soc. Electronics in Marine-ELMAR. A performance analysis of MPEG-4 encoder and decoder programs on a standard personal computer is presented. The paper first describes the MPEG-4 computational load and discusses related works, then outlines the performance analysis. Experimental results show that while the decoder program can be easily executed in real time, the encoder requires execution times in the order of seconds per frame which call for substantial optimisation to satisfy real-time constraints

Neural progenitor cell implants modulate vascular endothelial growth factor and brain-derived neurotrophic factor expression in rat axotomized neurons

Axotomy of central neurons leads to functional and structural alterations which largely revert when neural progenitor cells (NPCs) are implanted in the lesion site. The new microenvironment created by NPCs in the host tissue might modulate in the damaged neurons the expression of a high variety of molecules with relevant roles in the repair mechanisms, including neurotrophic factors. In the present work, we aimed to analyze changes in neurotrophic factor expression in axotomized neurons induced by NPC implants. For this purpose, we performed immunofluorescence followed by confocal microscopy analysis for the detection of vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3) and nerve growth factor (NGF) on brainstem sections from rats with axotomy of abducens internuclear neurons that received NPC implants (implanted group) or vehicle injections (axotomized group) in the lesion site. Control abducens internuclear neurons were strongly immunoreactive to VEGF and BDNF but showed a weak staining for NT-3 and NGF. Comparisons between groups revealed that lesioned neurons from animals that received NPC implants showed a significant increase in VEGF content with respect to animals receiving vehicle injections. However, the immunoreactivity for BDNF, which was increased in the axotomized group as compared to control, was not modified in the implanted group. The modifications induced by NPC implants on VEGF and BDNF content were specific for the population of axotomized abducens internuclear neurons since the neighboring abducens motoneurons were not affected. Similar levels of NT-3 and NGF immunolabeling were obtained in injured neurons from axotomized and implanted animals. Among all the analyzed neurotrophic factors, only VEGF was expressed by the implanted cells in the lesion site. Our results point to a role of NPC implants in the modulation of neurotrophic factor expression by lesioned central neurons, which might contribute to the restorative effects of these implants

Constraining GRB Emission Physics with Extensive Early-Time, Multiband Follow-up

Understanding the origin and diversity of emission processes responsible for Gamma-ray Bursts (GRBs) remains a pressing challenge. While prompt and contemporaneous panchromatic observations have the potential to test predictions of the internal-external shock model, extensive multiband imaging has been conducted for only a few GRBs. We present rich, early-time, multiband datasets for two \swift\ events, GRB 110205A and GRB 110213A. The former shows optical emission since the early stages of the prompt phase, followed by the steep rising in flux up to ~1000s after the burst ($t^{-\alpha}$ with $\alpha=-6.13 \pm 0.75$). We discuss this feature in the context of the reverse-shock scenario and interpret the following single power-law decay as being forward-shock dominated. Polarization measurements, obtained with the RINGO2 instrument mounted on the Liverpool Telescope, also provide hints on the nature of the emitting ejecta. The latter event, instead, displays a very peculiar optical to near-infrared lightcurve, with two achromatic peaks. In this case, while the first peak is probably due to the onset of the afterglow, we interpret the second peak to be produced by newly injected material, signifying a late-time activity of the central engine.Comment: 48 pages,11 figures, 24 tables. Accepted to The Astrophysical Journa

GRB070125: The First Long-Duration Gamma-Ray Burst in a Halo Environment

We present the discovery and high signal-to-noise spectroscopic observations of the optical afterglow of the long-duration gamma-ray burst GRB070125. Unlike all previously observed long-duration afterglows in the redshift range 0.5 < z 1.0 A) absorption features in the wavelength range 4000 - 10000 A. The sole significant feature is a weak doublet we identify as Mg II 2796 (W = 0.18 +/- 0.02 A), 2803 (W = 0.08 +/- 0.01) at z = 1.5477 +/- 0.0001. The low observed Mg II and inferred H I column densities are typically observed in galactic halos, far away from the bulk of massive star formation. Deep ground-based imaging reveals no host directly underneath the afterglow to a limit of R > 25.4 mag. Either of the two nearest blue galaxies could host GRB070125; the large offset (d >= 27 kpc) would naturally explain the low column density. To remain consistent with the large local (i.e. parsec scale) circum-burst density inferred from broadband afterglow observations, we speculate GRB070125 may have occurred far away from the disk of its host in a compact star-forming cluster. Such distant stellar clusters, typically formed by dynamical galaxy interactions, have been observed in the nearby universe, and should be more prevalent at z>1 where galaxy mergers occur more frequently.Comment: 8 pages, accepted in Ap