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Search Results: 1 - 10 of 148700 matches for " Joshua B. Rosales "
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Protein Phosphatase 1 β Paralogs Encode the Zebrafish Myosin Phosphatase Catalytic Subunit
Vaishali Jayashankar, Michael J. Nguyen, Brandon W. Carr, Dale C. Zheng, Joseph B. Rosales, Joshua B. Rosales, Douglas C. Weiser
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0075766
Abstract: Background The myosin phosphatase is a highly conserved regulator of actomyosin contractility. Zebrafish has emerged as an ideal model system to study the in vivo role of myosin phosphatase in controlling cell contractility, cell movement and epithelial biology. Most work in zebrafish has focused on the regulatory subunit of the myosin phosphatase called Mypt1. In this work, we examined the critical role of Protein Phosphatase 1, PP1, the catalytic subunit of the myosin phosphatase. Methodology/Principal Findings We observed that in zebrafish two paralogous genes encoding PP1β, called ppp1cba and ppp1cbb, are both broadly expressed during early development. Furthermore, we found that both gene products interact with Mypt1 and assemble an active myosin phosphatase complex. In addition, expression of this complex results in dephosphorylation of the myosin regulatory light chain and large scale rearrangements of the actin cytoskeleton. Morpholino knock-down of ppp1cba and ppp1cbb results in severe defects in morphogenetic cell movements during gastrulation through loss of myosin phosphatase function. Conclusions/Significance Our work demonstrates that zebrafish have two genes encoding PP1β, both of which can interact with Mypt1 and assemble an active myosin phosphatase. In addition, both genes are required for convergence and extension during gastrulation and correct dosage of the protein products is required.
Control of an Industrial SCR Catalyst Using Ceramic NOx Sensors  [PDF]
Joshua Schmitt, Daniel B. Olsen
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.33039
Abstract: Selective Catalytic Reduction (SCR) catalysts respond slowly to transient inputs, which is troublesome when designing ammonia feed controllers. An experimental SCR test apparatus installed on a slipstream of a Coo-per-Bessemer GMV-4, 2-stroke cycle natural gas engine is utilized. Ammonia (NH3) feed rate control algo-rithm development is carried out. Two control algorithms are evaluated: a feed forward control algorithm, using a pre ammonia injection ceramic NOx sensor and a feed forward plus feedback control algorithm, us-ing a pre ammonia injection ceramic NOx sensor and post catalyst ceramic NOx sensor to generate feedback signals. The feed forward algorithm controls to constant user input NH3/NOx molar ratio. The data show the lack of pressure compensation on the ceramic NOx sensors cause errors in feed forward NOx readings, re-sulting in sub optimal ammonia feed. The feedback system minimizes the post catalyst ceramic NOx sensor signal by adjusting the NH3/NOx molar ratio. The NOx sensors respond to ammonia + NOx; therefore, the feed forward plus feedback algorithm minimizes the sum of NOx emissions and ammonia slip. Successful application of the feedback control minimization technique is demonstrated with feedback periods of 15 and 5 minutes with molar ratio step sizes of 5 and 2.5%, respectively.
Stress Tolerance of Bed Bugs: A Review of Factors That Cause Trauma to Cimex lectularius and C. Hemipterus
Joshua B. Benoit
Insects , 2011, DOI: 10.3390/insects2020151
Abstract: Recent emergence of bed bugs ( Cimex spp.) has prompted a significant expansion of research devoted to this pest. The ability to survive and recover from stress has significant implications on the distribution and survival of insects, and bed bugs are no exception. Research on bed bug stress tolerance has shown considerable progress and necessitates a review on this topic. Bed bugs have an extraordinary ability to resist dehydration between bloodmeals, and this represents a critical factor allowing their prolonged survival when no host is available. High relative humidities are detrimental to bed bugs, leading to reduced survival in comparison to those held at lower relative humidities. Continual exposure of bed bugs, eggs and mobile stages, to temperatures below freezing and short term exposure (=1 h) to temperatures below ?16 to ?18 °C results in mortality. The upper thermal limit for short term exposure of eggs, nymphs and adults is between 40–45 °C for the common ( Cimex lectularius) and tropical ( C. hemipterus) bed bugs. Long-term exposure to temperatures above 35 °C results in significant reduction in survival of mobile bed bugs. Eggs for C. lectularius and C. hemipterus are no longer viable when held below 10 °C or above 37 °C throughout embryogenesis. Blood feeding, although necessary for survival and reproduction, is discussed as a stress due to thermal and osmotic fluctuations that result from ingesting a warm bloodmeal from a vertebrate host. Cold, heat, water stress and blood feeding prompted the expression of heat shock proteins (Hsps). Pesticide application is a common human-induced stress for urban pests, and recent studies have documented pesticide resistance in many bed bug populations. High levels of traumatic insemination (mating) of bed bugs has been linked to reduced survival and fecundity along with possibly exposing individuals to microbial infections after cuticular penetration by the paramere (=male reproductive organ), thus represents a form of sexual stress. Additionally, less common stress types such as microbial infections that have been documented in bed bugs will be discussed. Overall, this review provides a current update of research related to bed bug stress tolerance and how their ability to resist stressful conditions has lead to their expansion and proliferation.
The complex origin of Astyanax cavefish
Joshua B Gross
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-105
Abstract: Past population-level analyses have sought to: 1) estimate at what time in the geological past cave forms became isolated from surface-dwelling ancestors, 2) define the extent to which cave form populations originated from a common invasion (single origin hypothesis) or several invasions (multiple origin hypothesis), and 3) clarify the role of geological and climatic events in Astyanax cavefish evolution. In recent years, thanks to the combined use of morphological and genetic data, a much clearer picture has emerged regarding the origins of Astyanax cavefish.The consensus view, based on several recent studies, is that cave forms originated from at least two distinct ancestral surface-dwelling stocks over the past several million years. In addition, each stock gave rise to multiple invasions of the subterranean biotope. The older stock is believed to have invaded the El Abra caves at least three times while the new stock separately invaded the northern Guatemala and western Micos caves. This renewed picture of Astyanax cavefish origins will help investigators draw conclusions regarding the evolution of phenotypic traits through parallelism versus convergence. Additionally, it will help us understand how the presence of cave-associated traits in old versus young cave populations may be influenced by the time since isolation in the cave environment. This will, in turn, help to inform our broader understanding of the forces that govern the evolution of phenotypic loss.
Comment on: Increasing Exclusion: The Pauli Exclusion Principle and Energy Conservation for Bound Fermions are Mutually Exclusive arXiv:physics/0609190v4 [physics.gen-ph] by Jonathan Phillips
Joshua B. Halpern
Physics , 2007,
Abstract: Phillips incorrectly analyzes the ionization of He to conclude that the Pauli exclusion principle and conservation of energy are mutually exclusive. His error arises from neglect of electron repulsion, improper choices of energy zeros and other trivial errors.
Geometrically infinite surfaces in 3-manifolds with hyperbolic fundamental group
Joshua B. Barnard
Mathematics , 2005,
Abstract: We prove a partial generalization of Bonahon's tameness result to surfaces inside irreducible 3-manifolds with hyperbolic fundamental group. Bonahon's result states that geometrically infinite ends of freely indecomposable hyperbolic 3-manifolds are simply degenerate. It is easy to see that a geometrically infinite end gives rise to a sequence of curves on the corresponding surface whose geodesic representatives are not contained in any compact set. The main step in his proof is showing that one may assume that these curves are simple on the surface. In this paper, we generalize the main step of Bonahon's proof, showing that a geometrically infinite end gives rise to a sequence of simple surface curves whose geodesic representatives are not contained in any compact set.
Riparian and Riverine Wildlife Response to a Newly Created Bridge Crossing  [PDF]
Joshua A. Vance, Norse B. Angus, James T. Anderson
Natural Resources (NR) , 2012, DOI: 10.4236/nr.2012.34029
Abstract: Construction of man-made objects such as roads and bridges can influence wildlife presence and abundance. We investtigated waterbirds, songbirds, anurans, turtles, small mammals, and furbearers along the Ohio River, WV, at a new bridge crossing, a 45-year old bridge, and 1 or 2 islands with no bridge and at 3 distances from the bridge or center point at each site (0 m,100 m, and300 m). We sampled 19 waterbird, 60 songbird, 7 anuran, 5 turtle, 9 small mammal, and 4 furbearer species. Great blue heron (Ardea herodias) abundances were greater at the site with no bridge. Songbird composition differed among sites and between transects under and away from the bridge with higher abundances or association of rock pigeon (Columba livia) and cliff swallow (Petrochelidon pyrrhonota) under the bridges and lower abundances ofCarolinawren (Thryothorus ludovicianus) and common yellowthroat (Geothlypis trichas) under the bridges. Total small mammal abundance, diversity, and richness were lower under the new bridge compared to other sites and distances. We conclude that overall the new bridge is causing minimal relative abundance impacts to wildlife. However, great blue heron abundance may be altered due to noise and activity from the presence of the bridge and minor short-term impacts to some songbirds and small mammals directly under the bridge in the form of habitat conversion, fragmentation, and loss due to removal of vegetation is apparent.
Accelerated tests of coil coatings
Rosales, B. M.,Simancas, J.,Flores, S.
Revista de Metalurgia , 2003,
Abstract: Accelerated laboratory tests on 12 materials in study in the Subgroup 6 of the PATINA Network (CYTED), are discussed for different exposition periods in salt spray, SO2 and Prohesion chambers. International standards used to evaluate failures caused by the different aggressive agents of these laboratory tests are the same as those applied for outdoor expositions. The results exposed contribute to a better understanding of the mechanisms occurred in the diverse natural environments, being mentioned the main analogies and differences respect to factors affecting natural tests. They also allowed to evidence the advantages and limitations in the application of these tests during several days, as compared to the years required to attain similar failure magnitudes through outdoor tests. En este trabajo se discuten los ensayos de laboratorio acelerados, realizados sobre 12 materiales de estudio en el Subgrupo 6 de la Red PATINA (CYTED), a diferentes periodos de exposición en cámaras de niebla salina, SO2 y Prohesion. Se utilizaron las normas internacionales para evaluar los fallos causados por los diferentes agentes agresivos de estos ensayos de laboratorio, las cuales se aplican también para los ensayos de exposición a la intemperie. Los resultados expuestos contribuyen a una mejor comprensión de los mecanismos ocurridos en los diversos ambientes naturales, mencionándose las principales analogías y diferencias respecto de los factores que afectan los ensayos naturales. También permitieron evidenciar las ventajas y limitaciones en la aplicación de estos ensayos durante varios días, en comparación con los a os requeridos para alcanzar magnitudes de fallos similares por medio de ensayos a intemperie.
The Population Genetics of dN/dS
Sergey Kryazhimskiy,Joshua B. Plotkin
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000304
Abstract: Evolutionary pressures on proteins are often quantified by the ratio of substitution rates at non-synonymous and synonymous sites. The dN/dS ratio was originally developed for application to distantly diverged sequences, the differences among which represent substitutions that have fixed along independent lineages. Nevertheless, the dN/dS measure is often applied to sequences sampled from a single population, the differences among which represent segregating polymorphisms. Here, we study the expected dN/dS ratio for samples drawn from a single population under selection, and we find that in this context, dN/dS is relatively insensitive to the selection coefficient. Moreover, the hallmark signature of positive selection over divergent lineages, dN/dS>1, is violated within a population. For population samples, the relationship between selection and dN/dS does not follow a monotonic function, and so it may be impossible to infer selection pressures from dN/dS. These results have significant implications for the interpretation of dN/dS measurements among population-genetic samples.
Opportunities and Challenges for Successful Use of Bevacizumab in Pediatrics
Amy Barone,Joshua B. Rubin
Frontiers in Oncology , 2013, DOI: 10.3389/fonc.2013.00092
Abstract: Bevacizumab (Avastin) has rapidly gained status as a broadly active agent for malignancies of several different histologies in adults. This activity has spawned a range of uses in pediatrics for both oncologic and non-oncologic indications. Early analyses indicate that pediatric cancers exhibit a spectrum of responses to bevacizumab that suggest its activity may be more limited than in adult oncology. Most exciting, is that for low-grade tumors that threaten vision and hearing, there is not only evidence for objective tumor response but for recovery of lost function as well. In addition to oncological indications, there is a range of uses for non-oncologic disease for which bevacizumab has clear activity. Finally, a number of mechanisms have been identified as contributing to bevacizumab resistance in cancer. Elucidating these mechanisms will guide the development of future clinical trials of bevacizumab in pediatric oncology.
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