Estimating Self-Sustainability in Peer-to-Peer Swarming Systems

Peer-to-peer swarming is one of the \emph{de facto} solutions for distributed content dissemination in today's Internet. By leveraging resources provided by clients, swarming systems reduce the load on and costs to publishers. However, there is a limit to how much cost savings can be gained from swarming; for example, for unpopular content peers will always depend on the publisher in order to complete their downloads. In this paper, we investigate this dependence. For this purpose, we propose a new metric, namely \emph{swarm self-sustainability}. A swarm is referred to as self-sustaining if all its blocks are collectively held by peers; the self-sustainability of a swarm is the fraction of time in which the swarm is self-sustaining. We pose the following question: how does the self-sustainability of a swarm vary as a function of content popularity, the service capacity of the users, and the size of the file? We present a model to answer the posed question. We then propose efficient solution methods to compute self-sustainability. The accuracy of our estimates is validated against simulation. Finally, we also provide closed-form expressions for the fraction of time that a given number of blocks is collectively held by peers.Comment: 27 pages, 5 figure

Effects of motor imagery training of Parkinson's disease: a protocol for a randomized clinical trial

Background Gait disorders in individuals with Parkinson’s disease (PD) may be associated with alterations in the motor control system and aggravated by psychoemotional and cognitive issues. Therapeutic strategies aimed at self-perception and motor regulation seem to be promising. Motor imagery (MI) has been shown to be one of these strategies, but there is still no clear evidence of its applicability in this population. The aim of this trial is to determine the effects of motor-imagery training on the gait and electroencephalographic activity of individuals with PD. Methods/design The sample will consist of 40 individuals, aged between 45 and 75 years, in the mild and moderate phase of the disease, with the ability to generate voluntary mental images. They will be assessed for cognitive level, degree of physical disability, mental-image clarity, kinematic gait variables, electroencephalographic activity and mobility. Next, subjects will be randomly assigned to an experimental group (EG) and a control group (CG). The EG will perform motor imagery and gait, while the CG will only engage in gait exercises. Twelve training sessions will be conducted lasting up to 90 min each, three times a week, for 4 weeks. The subjects will be reassessed on the kinematic variables of gait, electroencephalographic activity and mobility at 1, 7 and 30 days after the final training session. Discussion The results may provide an important advance in neurological rehabilitation where an easy-access and low-cost intervention may help to improve gait, electroencephalographic activity and mobility in individuals with PD

Characterization, Classification And Analysis Of The Main Properties Of The Southwestern Goias Soil

Characterization of the soil and the grouping of its properties through main component analysis can assist in the classification and observation of the consequences of the conversion of native forest areas in pastures. Such data can aid in management practices. Considering the lack of studies in Cerrado soils of south-western Goias, developed metagranites of Jurubatuba suite, the objective was to classify and study the physical, chemical and mineralogical soil (under native forest and pasture) Southwest of Goias. Soil sampling and classification followed the Field Methods Manual and the Brazilian System of Soil Classification, respectively. The physical, chemical and mineralogical soil were studied, as well as main component analysis made for these attributes. The profile 1 under native forest was classified as "Cambissolo Háplico Tb eutrófico latossólico". The profile 2 under degraded pasture was rated "Latossolo Amarelo eutrófico típico". In addition, the profile 3 under rotated pasture was rated as "Latossolo Vermelho eutrófico chernossólico". It was observed that the "Latossolos" have higher bulk density and soil penetration resistance, indicating greater soil compaction. They showed high amounts of iron oxides and minor amount of nutrients such as calcium and magnesium. The principal component analysis allowed the grouping of profiles into two groups. Group 1 brought together the properties related to "Latossolos", and the second was related to "Cambissolo" properties. Thus, the principal components analysis aids the understanding of soil properties and the grouping of soils with similar characteristics, the level of order and management.3731135115

Influence Of A Cobalt-chromium Metal Framework On Surface Roughness And Knoop Hardness Of Visible Light-polymerized Acrylic Resins

Although visible light-polymerized acrylic resins have been used in removable partial dentures, it is not clear whether the presence of a metal framework could interfere with their polymerization, by possibly reflecting the light and affecting important properties, such as roughness and hardness, which would consequently increase biofilm accumulation. The aim of this study was to compare the roughness and Knoop hardness of a visible light-polymerized acrylic resin and to compare these values to those of water-bath- and microwave-polymerized resins, in the presence of a metal framework. Thirty-six specimens measuring 30.0 x 4.0 ± 0.5 mm of a microwave- (Onda Cryl), a visible light- (Triad) and a water-bath-polymerized (Clássico) (control) acrylic resins containing a cobalt-chromium metal bar were prepared. After processing, specimens were ground with 360 to 1000-grit abrasive papers in a polishing machine, followed by polishing with cloths and 1-μm diamond particle suspension. Roughness was evaluated using a profilometer (Surfcorder SE 1700) and Knoop hardness (Kg/mm 2) was assayed using a microhardness tester (Shimadzu HMV 2000) at distances of 50, 100, 200, 400 and 800 μm from the metal bar. Roughness and Knoop hardness means were submitted to two-way ANOVA and compared by Tukey and Kruskal Wallis tests at a 5% significance level Statistically significant differences were found (p<0.05) for roughness and Knoop hardness, with light-polymerized resin presenting the highest values (Ra = 0.11 μm and hardness between 20.2 and 21.4 Kg/mm 2). Knoop values at different distances from the metal bar did not differ statistically (p>0.05). Within the limitations of this in vitro study, it was concluded that the presence of metal did not influence roughness and hardness values of any of the tested acrylic resins.143208212Anusavice, K.J., (2003) Philip's Science of Dental Materials. 11 th Ed., p. 96. , 11 St. Louis: Elsevier ScienceBollen, C.M.L., Lambrechts, P., Quirynen, M., Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: A review of the literature (1997) Dent Mater, 13 (4), pp. 258-269Borchers, L., Tavassol, F., Tschernitschek, H., Surface quality achieved by polishing and by varnishing of temporary crown and fixed partial denture resins (1999) J Prosthet Dent, 82 (5), pp. 550-556Braun, K.O., Del Bel Cury, A.A., Cury, J.A., Use of microwave energy for processing acrylic resin near metal (1998) Braz Oral Res, 12 (2), pp. 173-180Curtis, D.A., Eggleston, T.L., Marshall, S.J., Watanabe, L.G., Shear bond strength of visible-light-cured resin relative to heat-cured resin (1989) Dental Mater, 5 (7), pp. 314-318De Clerck, J.P., Microwave polymerization of acrylic resins used in dental prosthesis (1987) J Prosthet Dent, 57 (5), pp. 650-658Khan, Z., Von Fraunhofer, J.A., Razavi, R., The staining characteristics, transverse strength, and microhardness of a visible light-cured denture base material (1987) J Prosthet Dent, 57 (3), pp. 384-386Levin, B., Sanders, J.L., Reitz, P.V., The use of microwave energy for processing acrylic resins (1989) J Prosthet Dent, 61 (3), pp. 381-383Ogle, R.E., Sorensen, S.E., Lewis, E.A., A new visible light-cured resin system applied to removable prosthodontics (1986) J Prosthet Dent, 56 (4), pp. 497-506Quirynen, M., Cml, B., Willems, G., Van Steenberghe, D., Comparison of surface characteristics of six commercially pure titanium abutments (1994) JOMI, 9 (1), pp. 71-76Reitz, P.V., Sanders, J.L., Levin, B., The curing of denture acrylic resins by microwave energy. Physical properties (1985) Quintessence Int, 6 (8), pp. 547-551Rodrigues Garcia, R.C.M., Souza Jr., J.A., Rached, R.N., Del Bel Cury, A.A., Effect of denture cleansers on the surface roughness and hardness of a microwave-cured acrylic resin and dental alloys (2004) J Prosthodont, 13 (3), pp. 1-6Rueggeberg, F.A., Goughman, W.F., Curtis Jr., J.W., Effect of light intensity and exposure duration on cure of resin composite (1994) Oper Dent, 19 (1), pp. 26-32Truong, V.T., Thomasz, F.G., Comparison of denture acrylic resins cured by boiling water and microwave energy (1988) Aust Dent J, 33 (3), pp. 201-204Ulusoy, M., Ulusoy, N., Aydin, A.K., An evaluation of polishing technique on surface roughness of acrylic rsins (1986) J Prosthetic Dent, 56 (1), pp. 107-11

Tratamiento conservador del hallux valgus juvenil mediante ortesis nocturnas

Se presentan los resultados obtenidos con tratamiento conservador del hallux valgus juvenil con el uso de ortesis nocturnas confeccionadas a medida, con material termoplástico, en 18 pacientes con edades de 8 a 15 años (media: 12 años). El tiempo medio de tratamiento fue de 18 meses y los pacientes fueron seguidos después del tratamiento por igual período de tiempo. Debe destacarse el alto abandono del método que alcanzó la cifra del 44%. Fueron utilizados como parámetros de valoración de resultados las medidas radiográficas de los ángulos de valguismo del hallux (AVH) e intermetatarsiano l-II (AIM), obtenidas antes y después de terminado el período de observación. El valor medio inicial del AVH fue de 22° y al final fue de 20°. Las medidas de los valores del AIM fueron 11 y 10,7°, respectivamente. Ambas medidas no se diferencian entre sí desde el punto de vista estadístico, lo que lleva a concluir que el tratamiento utilizado no fue capaz de corregir las deformidades básicas del hallus valgus infantil, pero evita la progresión de esas deformidades.The results of conservative treatment of adolescent hallux valgus using custom made nocturnal splints in 18 patients ranging in age from 8 to 15 years (mean 12) are presented. The average period of treatment and follow-up was 18 months. There was a high rate (44%) of treatment abandon. As assessment parameters were used radiographic measures of the hallux valgus angle and the intermetatarsal I-II angle. Measures were obtained before treatment and at the end of follow-up. The initial mean valgus angle was 22° and the last mean value 20°. The mean valus of the intermetatarsal angle were respectively 11° and 10,7°. There were no significant statistical differences, indicating that the treatment of hallux valgus using nocturnal splintage do not correct the deformity but avoid its progression

The Atp-dependent Rna Helicase Hrpb Plays An Important Role In Motility And Biofilm Formation In Xanthomonas Citri Subsp. Citri

Background: RNA helicases are enzymes that catalyze the separation of double-stranded RNA (dsRNA) using the free energy of ATP binding and hydrolysis. DEAD/DEAH families participate in many different aspects of RNA metabolism, including RNA synthesis, RNA folding, RNA-RNA interactions, RNA localization and RNA degradation. Several important bacterial DEAD/DEAH-box RNA helicases have been extensively studied. In this study, we characterize the ATP-dependent RNA helicase encoded by the hrpB (XAC0293) gene using deletion and genetic complementation assays. We provide insights into the function of the hrpB gene in Xanthomonas citri subsp. citri by investigating the roles of hrpB in biofilm formation on abiotic surfaces and host leaves, cell motility, host virulence of the citrus canker bacterium and growth in planta. Results: The hrpB gene is highly conserved in the sequenced strains of Xanthomonas. Mutation of the hrpB gene (Δ;hrpB) resulted in a significant reduction in biofilms on abiotic surfaces and host leaves. Δ;hrpB also exhibited increased cell dispersion on solid medium plates. Δ;hrpB showed reduced adhesion on biotic and abiotic surfaces and delayed development in disease symptoms when sprayed on susceptible citrus leaves. Quantitative reverse transcription-PCR assays indicated that deletion of hrpB reduced the expression of four type IV pili genes. The transcriptional start site of fimA (XAC3241) was determined using rapid amplification of 5′-cDNA Ends (5′RACE). Based on the results of fimA mRNA structure predictions, the fimA 5′ UTR may contain three different loops. HrpB may be involved in alterations to the structure of fimA mRNA that promote the stability of fimA RNA. Conclusions: Our data show that hrpB is involved in adherence of Xanthomonas citri subsp. citri to different surfaces. In addition, to the best of our knowledge, this is the first time that a DEAH RNA helicase has been implicated in the regulation of type IV pili in Xanthomonas. © 2016 Granato et al.16

Use Of Organic Compost Containing Waste From Small Ruminants In Corn Production

Composting is a useful way of transforming livestock waste into organic fertilizer, which is proven to increase soil nutrient levels, and thus crop yield. Remains from production and slaughter of small ruminants can become a source of important elements for plant growth, such as N, after microorganism-driven decomposition.The aim of this investigation was to evaluate the effects of this compost on soil fertility and on the nutritional status and yield of the corn crop. The experiment was conducted in a Haplic Luvisol in a randomized block design with six treatments and five application rates of the organic compound in Mg ha-1: 3 (half the standard rate), 6 (standard rate), 9 (one and a half times the standard rate), 12 (twice the standard rate), and 24 (four times the standard rate) and an additional treatment with mineral fertilizers (110, 50 e 30 kg ha-1 of N, P2O5 and K2O, respectively), with four blocks. Evaluations were performed for two harvests of rainfed crops, measuring soil fertility, nutritional status, and grain yield. The compost increased P, K, Na and Zn values in the 0.00-0.20 m layer in relation of mineral fertilization in 616, 21, 114 and 90% with rate 24 Mg ha-1 in second crop. Leaf N, Mg, and S contents, relative chlorophyll content, and the productivity of corn kernels increased in 27, 32, 36, 20 e 85%, respectively, of low rate (3 Mg ha-1) to high rate (24 Mg ha-1) with of application of the compost. Corn yield was higher with application of organic compost in rate of 24 Mg ha-1 than mineral fertilizer combination in second crop. © 2016, Revista Brasileira de Ciencia do Solo. All rights reserved.4

Quantitative image of fluorescence of ceramic and resin-cement veneers

The main of the study was quantify the effect of two ceramics with two underlying resin cements on apparent fluorescence levels. Buccal surfaces of two bovine incisors were ground flat producing one enamel and one dentin substrate. The veneers were fabricated (0.5 and 1.0 mm thickness) using two ceramics (IPSe. max Press and IPSe. max Zirpress, Ivoclar Vivadent). Veneers were cemented using either light-cured (Variolink II, Ivoclar Vivadent) or self-adhesive dual (Rely X U200, 3M ESPE) cement. The layered Control group materials had no cement application. Semi-quantitative fluorescence image analysis (Matlabs software, Matworks) involved processing the images as captured under each daylight (DL, Gretagmacbeth) and ultraviolet illuminants (UVA, Sylvania) within a neutral-gray lightbox (Macbeth Spectral Light). Statistical analysis of the quantitative fluorescence values was performed using two-way ANOVA and Tukey's test (p < 0.05). The e. max Zirpress on the dentin substrate produced greater fluorescence (p < 0.05) when subjected to UV illumination and more fluorescence (p < 0.05) than e. max Press in both cement groups. Light-cured cement produced higher (p < 0.05) fluorescence than the dual-cement with e. max Press on enamel under UV illumination. The fluorescence for e. max Press on the dentin substrate was greater (p < 0.05) than for e. max Zirpress using dual self-adhesive cement subjected to daylight illumination. Thus, it is possible to conclude that the combination of ceramic and cement produce definite, significant effects on the apparent fluorescence, vital quality for restorative dentistry3

Draft Genome Sequence Of 11399, A Transformable Citrus-pathogenic Strain Of Xylella Fastidiosa

The draft genome of Xylella fastidiosa subsp. pauca strain 11399, a transformable citrus-pathogenic strain, is reported here. The 11399 genome size is 2,690,704 bp and has a G+C content of 52.7%. The draft genome of 11399 reveals the absence of four type I restriction-modification system genes. © 2016 Niza et al.4