900 research outputs found
A survey of potential architectures for communication in heterogeneous networks
An increasingly wireless world will mean that devices with multiple network interfaces will soon become commonplace. Users will expect to be always connected from anywhere and at any time as connections will be switched to available networks using handover techniques. However, different networks have different Qualities-of-Service so a Quality-of-Service Framework is needed to help applications and services deal with this new environment. In addition, since these networks must work together, future mobile systems will have an open, instead of the currently closed, architecture. Therefore new mechanisms will be needed to protect users, servers and network infrastructure. This means that future mobile networks will have to integrate communications, mobility, quality-of service and security. This paper provides an overview of potential architectures for communication in future networks. Our study shows that only a number of these architectures support this integration
Uneven Relationalities, Collective Biography, and Sisterly Affect in Neoliberal Universities
This article deploys a collective biographical methodology as a political and epistemological intervention in order to explore the emotional and affective politics of academic work for women in neoliberal universities. The managerial practices of contemporary universities tend to elevate disembodied reason over emotion; to repress, commodify, or co-opt emotional and affective labor; to increase individualization and competition among academic workers; and to disregard the relational work that the article suggests is essential for well-being at work. The apparent marginalization of feminist and feminine ways of being, thinking, and feeling in academia is examined through close readings of three narrative vignettes, which are based on memories of the everyday academic spaces of meetings, workshops, and mentoring. These stories explore moments of the breaking of ties among women and between men and women, as well as document how feminist relationalities can bind and exclude. The article suggests that academic ties are both part of the problem and the solution to countering
neoliberal policies, and that academic relationships, especially with other women, are often experienced as unrealized spaces of hope. Building on feminist scholarship about race and diversity, the article reflects on how relational practices like collective biography create both inclusions and exclusions. Nevertheless, it suggests that the methodology of collective biography might engender more sustainable and ethical ways of being in academic workplaces because it provides the resources to begin to create a new collective imaginary of academia
Fish Distributions and Nutrient Cycling in Streams: Can Fish Create Biogeochemical Hotspots?
Rates of biogeochemical processes often vary widely in space and time, and characterizing this variation is critical for understanding ecosystem functioning. In streams, spatial hotspots of nutrient transformations are generally attributed to physical and microbial processes. Here we examine the potential for heterogeneous distributions of fish to generate hotspots of nutrient recycling. We measured nitrogen (N) and phosphorus (P) excretion rates of 47 species of fish in an N-limited Neotropical stream, and we combined these data with population densities in each of 49 stream channel units to estimate unit- and reach-scale nutrient recycling. Species varied widely in rates of N and P excretion as well as excreted N:P ratios (6–176 molar). At the reach scale, fish excretion could meet \u3e75% of ecosystem demand for dissolved inorganic N and turn over the ambient NH4 pool i
Fish Distributions And Nutrient Cycling In Streams: Can Fish Create Biogeochemical Hotspots
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117137/1/ecy20088982335.pd
Gene expression profiling of brains from bovine spongiform encephalopathy (BSE)-infected cynomolgus macaques
BACKGROUND:
Prion diseases are fatal neurodegenerative disorders whose pathogenesis mechanisms are not fully understood. In this context, the analysis of gene expression alterations occurring in prion-infected animals represents a powerful tool that may contribute to unravel the molecular basis of prion diseases and therefore discover novel potential targets for diagnosis and therapeutics. Here we present the first large-scale transcriptional profiling of brains from BSE-infected cynomolgus macaques, which are an excellent model for human prion disorders.
RESULTS:
The study was conducted using the GeneChip\uae Rhesus Macaque Genome Array and revealed 300 transcripts with expression changes greater than twofold. Among these, the bioinformatics analysis identified 86 genes with known functions, most of which are involved in cellular development, cell death and survival, lipid homeostasis, and acute phase response signaling. RT-qPCR was performed on selected gene transcripts in order to validate the differential expression in infected animals versus controls. The results obtained with the microarray technology were confirmed and a gene signature was identified. In brief, HBB and HBA2 were down-regulated in infected macaques, whereas TTR, APOC1 and SERPINA3 were up-regulated.
CONCLUSIONS:
Some genes involved in oxygen or lipid transport and in innate immunity were found to be dysregulated in prion infected macaques. These genes are known to be involved in other neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Our results may facilitate the identification of potential disease biomarkers for many neurodegenerative diseases
Effect of some factors of variability on carcass weight of organically reared beef.
..Introduction - During the last few years, organic production has showed an increasing trend. This trend is mainly due to the EU supporting policy, in order to guarantee food security and sustainable productions for the future. In addition, since the nineties, producers and consumers have shown a growing interest towards organic production and the market have been developed. Moreover in Tuscany, a lot of farmers which own marginal land and/or forested areas have decided to turn to organic livestock, both for the ethical value of their products and for the greater bargaining power that the goods have on the market.
Aim - The aim of this research was to study the effects of some variability factors on carcass weight.
Materials and methods - Breed, slaughtering age, sex, season of birth, interactions year x management, breed x age and sex x age on carcass weight of 457 cattle slaughtered during the period 2001-2011 were evaluated. The animals were Chianina, Maremmana, Limousine and crossbreed Maremmana x Limousine veals and were raised in the same farm in Tuscany. The animals received the same feed and were slaughtered at an average age of 18/24 months, depending on the breed and sex. Data were stratified on the basis of the slaughtering age (five levels), then a statistical analysis was performed.
Results and discussion - Chianina and crossbreed Limousine x Maremmana gave heavier carcasses: 389.3 +/- 6.39 and 323.4 +/- 5.41 kg, respectively. In general the farming system (conventional or organic) did not affect carcass weight. Chianina cattle showed a wide range of slaughtering weights. Moreover in the farm, the larger number of Chianina beef was slaughtered between 22 and 26 months like Limousine and crossbreeds, whereas Maremmana was slaughtered between 18-22 months. Males had heavier carcass than female: 353.2 +/- 4.35 vs 299.4 +/- 5.85 respectively but the differences between sexes were significant only after 18 months. The management system (conventional/organic) and the season of birth did not affect the carcass weight of cattle.
Conclusion - The management system (conventional/organic) do not seem to influence the productivity, indeed it does not affect the carcass weight of beef cattle. On the other hands the choices of management play an important roles on productivity as demonstrated by the effects of the slaughter age and the breed on the carcass weight
Post-Acute COVID-19 Joint Pain and New Onset of Rheumatic Musculoskeletal Diseases: A Systematic Review
As the number of reports of post-acute COVID-19 musculoskeletal manifestations is rapidly rising, it is important to summarize the current available literature in order to shed light on this new and not fully understood phenomenon. Therefore, we conducted a systematic review to provide an updated picture of post-acute COVID-19 musculoskeletal manifestations of potential rheumatological interest, with a particular focus on joint pain, new onset of rheumatic musculoskeletal diseases and presence of autoantibodies related to inflammatory arthritis such as rheumatoid factor and anti-citrullinated protein antibodies. We included 54 original papers in our systematic review. The prevalence of arthralgia was found to range from 2% to 65% within a time frame varying from 4 weeks to 12 months after acute SARS-CoV-2 infection. Inflammatory arthritis was also reported with various clinical phenotypes such as symmetrical polyarthritis with RA-like pattern similar to other prototypical viral arthritis, polymyalgia-like symptoms, or acute monoarthritis and oligoarthritis of large joints resembling reactive arthritis. Moreover, high figures of post-COVID-19 patients fulfilling the classification criteria for fibromyalgia were found, ranging from 31% to 40%. Finally, the available literature about prevalence of rheumatoid factor and anti-citrullinated protein antibodies was largely inconsistent. In conclusion, manifestations of rheumatological interest such as joint pain, new-onset inflammatory arthritis and fibromyalgia are frequently reported after COVID-19, highlighting the potential role of SARS-CoV-2 as a trigger for the development of autoimmune conditions and rheumatic musculoskeletal diseases
The coordination of cell growth during fission yeast mating requires Ras1-GTP hydrolysis
The spatial and temporal control of polarity is fundamental to the survival of all organisms. Cells define their polarity using highly conserved mechanisms that frequently rely upon the action of small GTPases, such as Ras and Cdc42. Schizosaccharomyces pombe is an ideal system with which to study the control of cell polarity since it grows from defined tips using Cdc42-mediated actin remodeling. Here we have investigated the importance of Ras1-GTPase activity for the coordination of polarized cell growth during fission yeast mating. Following pheromone stimulation, Ras1 regulates both a MAPK cascade and the activity of Cdc42 to enable uni-directional cell growth towards a potential mating partner. Like all GTPases, when bound to GTP, Ras1 adopts an active conformation returning to an inactive state upon GTP-hydrolysis, a process accelerated through interaction with negative regulators such as GAPs. Here we show that, at low levels of pheromone stimulation, loss of negative regulation of Ras1 increases signal transduction via the MAPK cascade. However, at the higher concentrations observed during mating, hyperactive Ras1 mutations promote cell death. We demonstrate that these cells die due to their failure to coordinate active Cdc42 into a single growth zone resulting in disorganized actin deposition and unsustainable elongation from multiple tips. These results provide a striking demonstration that the deactivation stage of Ras signaling is fundamentally important in modulating cell polarity
Whole-lake experiments trace added terrestrial particulate organic carbon in benthic food webs of shallow lakes
Lake ecosystems are strongly linked to their terrestrial surroundings by material and energy fluxes across ecosystem boundaries. However, the contribution of terrestrial particulate organic carbon (tPOC) from annual leaf fall to lake food webs has not yet been adequately traced and quantified. In this study, we conducted whole-lake experiments to trace artificially added tPOC through the food webs of two shallow lakes of similar eutrophic status, but featuring alternative stable regimes (macrophyte rich vs. phytoplankton dominated). Lakes were divided with a curtain, and maize (Zea mays) leaves were added, as an isotopically distinct tPOC source, into one half of each lake. To estimate the balance between autochthonous carbon fixation and allochthonous carbon input, primary production and tPOC and tDOC (terrestrial dissolved organic carbon) influx were calculated for the treatment sides. We measured the stable isotope ratios of carbon (δ13C) of about 800 samples from all trophic consumer levels and compared them between lake sides, lakes, and three seasons. Leaf litter bag experiments showed that added maize leaves were processed at rates similar to those observed for leaves from shoreline plants, supporting the suitability of maize leaves as a tracer. The lake-wide carbon influx estimates confirmed that autochthonous carbon fixation by primary production was the dominant carbon source for consumers in the lakes. Nevertheless, carbon isotope values of benthic macroinvertebrates were significantly higher with maize additions compared to the reference side of each lake. Carbon isotope values of omnivorous and piscivorous fish were significantly affected by maize additions only in the macrophyte-dominated lake and δ13C of zooplankton and planktivorous fish remained unaffected in both lakes. In summary, our results experimentally demonstrate that tPOC in form of autumnal litterfall is rapidly processed during the subsequent months in the food web of shallow lakes and is channeled to secondary and tertiary consumers predominantly via the benthic pathways. A more intense processing of tPOC seems to be connected to a higher structural complexity in littoral zones, and hence may differ between shallow lakes of alternative stable states
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