OALib Journal期刊

ISSN: 2333-9721



匹配條件: “Ryan Wasserman” ,找到相關結果約4350條。
Diet of largemouth bass, Micropterus salmoides (Centrarchidae) an invasive alien in the lower reaches of an Eastern Cape River, South Africa
Ryan Wasserman,Nadine Strydom,Olaf Weyl
African Zoology , 2012,
Abstract: Largemouth bass (Micropterus salmoides) have been introduced to many South African river systems where they become invasive and pose a threat to native biota. The diets of small (32 - 138mm TL) and large (192 - 448mm TL) sized bass were analyzed and compared in a marine fish nursery area in the lower Kowie River on the warm temperate coast of South Africa over a one year period from March 2009 to February 2010. Dietary differences were detected between the two size groups. Amphipod sp. (% Index of Relative Importance (IRI) = 69.2) and dipterans (Insecta) (%IRI = 21.9) dominated gut contents of small bass while larger bass preyed mostly on odonates (Insecta) (%IRI = 16.3) and the brachyuran Potamonautes sidneyi (%IRI = 80.0). Fish prey was of low importance during this study but comparisons with previous work on the lower Kowie River showed that when the river is flowing, young marine fish recruiting into the freshwater from the estuary become important prey items. These data suggest that in the lower Kowie River bass utilise invertebrate prey at low fish prey abundance and opportunistically feed on migrant fish when these are available.
Uniform Asymptotic Inference and the Bootstrap After Model Selection
Ryan J. Tibshirani,Alessandro Rinaldo,Robert Tibshirani,Larry Wasserman
Statistics , 2015,
Abstract: Recently, Taylor et al. (2014) developed a method for making inferences on parameters after model selection, in a regression setting with normally distributed errors. In this work, we study the large sample properties of this method, without assuming normality. We prove that the test statistic of Taylor et al. (2014) is asymptotically pivotal, as the number of samples n grows and the dimension d of the regression problem stays fixed; our asymptotic result is uniformly valid over a wide class of nonnormal error distributions. We also propose an efficient bootstrap version of this test that is provably (asymptotically) conservative, and in practice, often delivers shorter confidence intervals that the original normality-based approach. Finally, we prove that the test statistic of Taylor et al. (2014) does not converge uniformly in a high-dimensional setting, when the dimension d is allowed grow. Recently, developed a method for making inferences on parameters after model selection. In this work, we explore the large sample properties of this method. We present results about the uniform convergence of the test statistic proposed by Taylor et al. (2014), and we propose computationally efficient bootstrap version of the method.
The Toll-Like receptor adaptor TRIF contributes to otitis media pathogenesis and recovery
Anke Leichtle, Michelle Hernandez, Kwang Pak, Nicholas J Webster, Stephen I Wasserman, Allen F Ryan
BMC Immunology , 2009, DOI: 10.1186/1471-2172-10-45
Abstract: Expression of TRIF mRNA was only modesty enhanced during OM, but both type I IFN signalling genes and type I IFN-inducible genes were significantly up-regulated in WT mice. TRIF-deficient mice showed reduced but more persistent mucosal hyperplasia and less leukocyte infiltration into the ME in response to NTHi infection than did WT animals. Viable bacteria could be cultured from MEs of TRIF-/- mice for much longer in the course of disease than was the case for middle ears of WT mice.Our results demonstrate that activation of TRIF/type I IFN responses is important in both the pathogenesis and resolution of NTHi-induced OM.Otitis media (OM) is the most common pediatric disease in industrialized nations [1,2]. OM is characterized by hyperplasia of the middle ear (ME) mucosa, the development of effusion, and leukocytic infiltration of the ME [3,4]. The etiology of OM is multifactorial, with Eustachian tube dysfunction, prior viral infection and allergy [5-7] all being factors known to contribute to OM incidence. However, bacterial infection is common to most acute and/or recurrent OM. Non-typeable Haemophilus influenzae (NTHi), which since the introduction of pneumococcal vaccines is associated with an increasing percentage of OM [8], is one of the most common pathogens isolated from the ME in OM.NTHi can influence host cells through interaction with pattern recognition receptors, which recognize molecules produced by pathogens and which play a key role in innate immunity. They serve as the first line of host defense in infection, and they include the family of Toll-like receptors (TLRs). As illustrated in Figure 1, TLR activation induces pro-inflammatory cytokines such as interleukins (ILs), tumor necrosis factor alpha (TNFα) and type I interferons (IFNs), via signaling cascades including those dependent upon the MyD88-NFkB, TRIF-IRF3 and/or MAP kinase pathways. All TLRs except TLR3 recruit the adaptor MyD88 (Myeloid differentiation primary response gene 88), which can
Trophic Level Stability-Inducing Effects of Predaceous Early Juvenile Fish in an Estuarine Mesocosm Study
Ryan J. Wasserman, Margaux Noyon, Trevor S. Avery, P. William Froneman
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061019
Abstract: Background Classically, estuarine planktonic research has focussed largely on the physico-chemical drivers of community assemblages leaving a paucity of information on important biological interactions. Methodology/Principal Findings Within the context of trophic cascades, various treatments using in situ mesocosms were established in a closed estuary to highlight the importance of predation in stabilizing estuarine plankton abundances. Through either the removal (filtration) or addition of certain planktonic groups, five different trophic systems were established. These treatments contained varied numbers of trophic levels and thus different “predators” at the top of the food chain. The abundances of zooplankton (copepod and polychaete), ciliate, micro-flagellate, nano-flagellate and bacteria were investigated in each treatment, over time. The reference treatment containing apex zooplanktivores (early juvenile mullet) and plankton at natural densities mimicked a natural, stable state of an estuary. Proportional variability (PV) and coefficient of variation (CV) of temporal abundances were calculated for each taxon and showed that apex predators in this experimental ecosystem, when compared to the other systems, induced stability. The presence of these predators therefore had consequences for multiple trophic levels, consistent with trophic cascade theory. Conclusions/Significance PV and CV proved useful indices for comparing stability. Apex predators exerted a stabilizing pressure through feeding on copepods and polychaetes which cascaded through the ciliates, micro-flagellates, nano-flagellates and bacteria. When compared with treatments without apex predators, the role of predation in structuring planktonic communities in closed estuaries was highlighted.
Nonparametric Modal Regression
Yen-Chi Chen,Christopher R. Genovese,Ryan J. Tibshirani,Larry Wasserman
Statistics , 2014,
Abstract: Modal regression estimates the local modes of the distribution of Y given X = x, instead of the mean, as in the usual regression sense, and can hence reveal important structure missed by usual regression methods. We study a simple nonparametric method for modal regression, based on a kernel density estimate (KDE) of the joint distribution of Y and X. We derive asymptotic error bounds for this method, and propose techniques for constructing confidence sets and prediction sets. The latter is used to select the smoothing bandwidth of the underlying KDE. The idea behind modal regression is connected to many others, such as mixture regression and density ridge estimation, and we discuss these ties as well.
A Mouse Model of Otitis Media Identifies HB-EGF as a Mediator of Inflammation-Induced Mucosal Proliferation
Keigo Suzukawa, Julia Tomlin, Kwang Pak, Eduardo Chavez, Arwa Kurabi, Andrew Baird, Stephen I. Wasserman, Allen F. Ryan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102739
Abstract: Objective Otitis media is one of the most common pediatric infections. While it is usually treated without difficulty, up to 20% of children may progress to long-term complications that include hearing loss, impaired speech and language development, academic underachievement, and irreversible disease. Hyperplasia of middle ear mucosa contributes to the sequelae of acute otitis media and is of important clinical significance. Understanding the role of growth factors in the mediation of mucosal hyperplasia could lead to the development of new therapeutic interventions for this disease and its sequelae. Methods From a whole genome gene array analysis of mRNA expression during acute otitis media, we identified growth factors with expression kinetics temporally related to hyperplasia. We then tested these factors for their ability to stimulate mucosal epithelial growth in vitro, and determined protein levels and histological distribution in vivo for active factors. Results From the gene array, we identified seven candidate growth factors with upregulation of mRNA expression kinetics related to mucosal hyperplasia. Of the seven, only HB-EGF (heparin-binding-epidermal growth factor) induced significant mucosal epithelial hyperplasia in vitro. Subsequent quantification of HB-EGF protein expression in vivo via Western blot analysis confirmed that the protein is highly expressed from 6 hours to 24 hours after bacterial inoculation, while immunohistochemistry revealed production by middle ear epithelial cells and infiltrating lymphocytes. Conclusion Our data suggest an active role for HB-EGF in the hyperplasia of the middle ear mucosal epithelium during otitis media. These results imply that therapies targeting HB-EGF could ameliorate mucosal growth during otitis media, and thereby reduce detrimental sequelae of this childhood disease.
Relato histórico e identidad nacional en la nomenclatura de Montevideo de 1843
Memoria y Sociedad , 2010,
Abstract: this article examines the names of streets, squares and markets in montevideo, thought in 1843 by the romantic writer and politician andrés lamas. it takes in account the conditions of intellectual and political production that led his design. in these names, which referto local history and geography, the author willed to provide a narrative that could strength uruguayan national identity. such intention is clear in a text in which he explains the reasons of his choice. to this respect, it is a very interesting initiative to explore the current problems that emerged by mid 19th century when anybody wanted to elaborate historical stories to sustain national identities in the rio de la plata.
Universum (Talca) , 2010, DOI: 10.4067/S0718-23762010000200013
Abstract: development and integration were issues presents in the worries of intellectuals, politicians and diplomats. in the period between 1945 and 1964, those themes were particularly important. the aim of the article is bring to public some of these proposals, enabling to find the nuances of the meanings and contents embedded by those subjects in the populist period, but also revealing the ideologies about development and integration in the different governments, intellectuals groups and diplomatic personal.
Is our media (still) racist?
Herman Wasserman
Global Media Journal : African Edition , 2011, DOI: 10.5789/1-1-53
Abstract: The question requires more than a yes or no answer. If racism exists, it is certainly not for a lack of attempts to rid the media from the shackles of its history under apartheid. Since democracy arrived in South Africa, the media industry has undergone some wide-ranging changes. On the level of ownership and editorial changes, the industry has seen ownership of large media houses pass to black consortia and the appointment of black editors and journalists to previously white-dominated media institutions. On the level of professionalism, the system of self-regulation entered into has attempted to ensure that media content is rid of racist stereotyping. The Press Ombudsman’s code cautions the media to “avoid discriminatory or denigrator references to people's race, colour, ethnicity, religion, gender, sexual orientation or preference, physical or mental disability or illness, or age”, unless it “is strictly relevant to the matter reported or adds significantly to readers' understanding of that matter”. It also warns against hate speech, as does the Broadcasting Complaints Commission of South Africa’s code, based on the values enshrined in the Constitution. So do we still need to think about racism in the South African media?
A primeira fase da historiografia latino-americana e a constru o da identidade das novas na es
Claudia Wasserman
História da Historiografia , 2011,
Abstract: O objetivo deste artigo é examinar as propostas e afirma es a respeito da identidade nacional na historiografia latino-americana a partir do movimento da independência no come o do século XIX e no período imediatamente pós-emancipa o. Com base em excertos das obras produzidas por autores clássicos a respeito das origens da na o e das identidades nacionais na América Latina do século XIX, o artigo pretende encontrar regularidades no discurso historiográfico da regi o. Ser o abordadas especialmente as quest es sobre as origens das na es, os obstáculos a serem transpostos para sua constitui o plena e a ado o de modelos externos.

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