9,990 research outputs found
Measurements of the CKM angle beta in charmless loop-dominated B meson decays at BaBar
We report on preliminary measurements of time-dependent CP-violation
asymmetries in charmless neutral B meson decays to K+K-K0 (including resonant
decays phiK0 and f0K0), eta'K0, pi0K0s, K0sK0sK0s, K0sK0s, rho0K0s, omegaK0s.
The results are obtained from a data sample of up to 347 million BBbar pairs
produced by e+e- annihilation at the Y(4S) resonance collected with the BaBar
detector at the PEP-2 asymmetric-energy B-meson Factory at SLAC.Comment: 6 pages, contributed to the Proceedings of ICHEP200
Measurements of CKM angles beta/phi_1 and alpha/phi_2 at the BABAR and Belle experiments
We report measurements of the CKM angles beta/phi_1 and alpha/phi_2 done by
the BABAR and Belle experiments. Both experiments have collected large data
samples, corresponding to a total of more than 1 billion of BBbar pairs, at the
e^+e^- asymmetric-energy colliders PEP-II (SLAC) and KEK-B (KEK), respectively.Comment: 6 pages, 1 postscript figure, contributed to the Proceedings of Heavy
Quarks and Leptons, Melbourne, 200
A silicon model of auditory localization
The barn owl accurately localizes sounds in the azimuthal plane, using interaural time difference as a cue. The time-coding pathway in the owl's brainstem encodes a neural map of azimuth, by processing interaural timing information. We have built a silicon model of the time-coding pathway of the owl. The integrated circuit models the structure as well as the function of the pathway; most subcircuits in the chip have an anatomical correlate. The chip computes all outputs in real time, using analog, continuous-time processing
A Fast Splitting Method for efficient Split Bregman Iterations
In this paper we propose a new fast splitting algorithm to solve the Weighted
Split Bregman minimization problem in the backward step of an accelerated
Forward-Backward algorithm. Beside proving the convergence of the method,
numerical tests, carried out on different imaging applications, prove the
accuracy and computational efficiency of the proposed algorithm
A probabilistic approach to quantifying hydrologic thresholds regulating migration of adult Atlantic salmon into spawning streams
Acknowledgment Data to support this study are provided by the Marine Scotland Science Freshwater Laboratory (MSS-FL) and are available for free download on line [Glover and Malcolm, 2015a, 2015b].Peer reviewedPublisher PD
A transcriptional regulatory mechanism finely tunes the firing of type VI secretion system in response to bacterial enemies
The ability to detect and measure danger from an environmental signal is paramount for bacteria to respond accordingly, deploying strategies that halt or counteract potential cellular injury and maximize survival chances. Type VI secretion systems (T6SSs) are complex bacterial contractile nanomachines able to target toxic effectors into neighboring bacteria competing for the same colonization niche. Previous studies support the concept that either T6SSs are constitutively active or they fire effectors in response to various stimuli, such as high bacterial density, cell-cell contact, nutrient depletion, or components from dead sibling cells. For Serratia marcescens, it has been proposed that its T6SS is stochastically expressed, with no distinction between harmless or aggressive competitors. In contrast, we demonstrate that the Rcs regulatory system is responsible for finely tuning Serratia T6SS expression levels, behaving as a transcriptional rheostat. When confronted with harmless bacteria, basal T6SS expression levels suffice for Serratia to eliminate the competitor. A moderate T6SS upregulation is triggered when, according to the aggressor-prey ratio, an unbalanced interplay between homologous and heterologous effectors and immunity proteins takes place. Higher T6SS expression levels are achieved when Serratia is challenged by a contender like Acinetobacter, which indiscriminately fires heterologous effectors able to exert lethal cellular harm, threatening the survival of the Serratia population. We also demonstrate that Serratiaâs RcsB-dependent T6SS regulatory mechanism responds not to general stress signals but to the action of specific effectors from competitors, displaying an exquisite strategy to weigh risks and keep the balance between energy expenditure and fitness costs. IMPORTANCE Serratia marcescens is among the health-threatening pathogens categorized by the WHO as research priorities to develop alternative antimicrobial strategies, and it was also recently identified as one major component of the gut microbiome in familial Crohn disease dysbiosis. Type VI secretion systems (T6SSs) stand among the array of survival strategies that Serratia displays. They are contractile multiprotein complexes able to deliver toxic effectors directed to kill bacterial species sharing the same niche and, thus, competing for vital resources. Here, we show that Serratia is able to detect and measure the extent of damage generated through T6SS-delivered toxins from neighboring bacteria and responds by transcriptionally adjusting the expression level of its own T6SS machinery to counterattack the rival. This strategy allows Serratia to finely tune the production of costly T6SS devices to maximize the chances of successfully fighting against enemies and minimize energy investment. The knowledge of this novel mechanism provides insight to better understand bacterial interactions and design alternative treatments for polymicrobial infections.Fil: Lazzaro, Martina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂa Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de BiologĂa Molecular y Celular de Rosario; ArgentinaFil: Feldman, Mario F.. Washington University in St. Louis; Estados UnidosFil: Garcia Vescovi, Eleonora. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Rosario. Instituto de BiologĂa Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias BioquĂmicas y FarmacĂ©uticas. Instituto de BiologĂa Molecular y Celular de Rosario; Argentin
Increasing the Efficiency of Sparse Matrix-Matrix Multiplication with a 2.5D Algorithm and One-Sided MPI
Matrix-matrix multiplication is a basic operation in linear algebra and an
essential building block for a wide range of algorithms in various scientific
fields. Theory and implementation for the dense, square matrix case are
well-developed. If matrices are sparse, with application-specific sparsity
patterns, the optimal implementation remains an open question. Here, we explore
the performance of communication reducing 2.5D algorithms and one-sided MPI
communication in the context of linear scaling electronic structure theory. In
particular, we extend the DBCSR sparse matrix library, which is the basic
building block for linear scaling electronic structure theory and low scaling
correlated methods in CP2K. The library is specifically designed to efficiently
perform block-sparse matrix-matrix multiplication of matrices with a relatively
large occupation. Here, we compare the performance of the original
implementation based on Cannon's algorithm and MPI point-to-point
communication, with an implementation based on MPI one-sided communications
(RMA), in both a 2D and a 2.5D approach. The 2.5D approach trades memory and
auxiliary operations for reduced communication, which can lead to a speedup if
communication is dominant. The 2.5D algorithm is somewhat easier to implement
with one-sided communications. A detailed description of the implementation is
provided, also for non ideal processor topologies, since this is important for
actual applications. Given the importance of the precise sparsity pattern, and
even the actual matrix data, which decides the effective fill-in upon
multiplication, the tests are performed within the CP2K package with
application benchmarks. Results show a substantial boost in performance for the
RMA based 2.5D algorithm, up to 1.80x, which is observed to increase with the
number of involved processes in the parallelization.Comment: In Proceedings of PASC '17, Lugano, Switzerland, June 26-28, 2017, 10
pages, 4 figure
THE SUPPORT OF GENE EXPRESSION IN UNDERSTANDING SECONDARY METABOLITE PRODUCTION AND ECOLOGY IN FUSARIUM VERTICILLIOIDES
Il tema principale di questa tesi di dottorato verte sul metabolismo secondario di F. verticillioides, con particolare interesse alla via biosintetica, produzione e mascheramento delle fumonisine B (FB), fumonisine A (FA), fumonisine C (FC) e bikaverina, studiati in relazione allâecologia fungina.
Eâ stato osservato che lâacqua libera (aw) esercita un effetto significativo maggiore rispetto alla temperatura sul metabolismo secondario di F. verticillioides. Alti valori di aw favoriscono lâespressione dei geni FUM ed una maggiore sintesi delle FB, FA e FC. Inoltre la produzione di bikaverina e lâespressione di BIK1 sono influenzate dallâ aw nello stesso modo che la produzione di FB e lâespressione dei geni FUM.
Anche il tempo di incubazione Ăš un fattore critico per la produzione di FB in F. verticillioides, cosĂŹ come per F. proliferatum: la produzione di FB, FA e FC aumenta nel tempo fino a 30 giorni, periodo dopo il quale si notano differenze tra le due specie fungine.
Riguardo le fumonisine nascoste, queste sono state ritrovate in colture sia di F. verticillioides che di F. proliferatum. Non Ăš stata registrata sintesi alcuna in colture cresciute su substrato di crescita sintetico, ma al contrario solo su colture cresciute su substrato a base di mais.The main topic of this PhD thesis is F. verticillioides secondary metabolism, with regard to fumonisin B (FB), fumonisin A (FA), fumonisin C (FC) and bikaverin biosynthetic pathways and production and masking, studied in relation to fungal ecology.
What we found is that water activity (aw) has a more significant effect than temperature on F. verticillioides secondary metabolism. Moreover bikaverin production and BIK1 expression are influenced by aw in the same way as FB production and FUM gene expression respectively.
High aw levels favour FUM gene expression and allow the highest synthesis of FB, FA and FC. Incubation time is also critical for FB production both for F. verticillioides and F. proliferatum: the general trend is that FB, FA and FC production increases with time, up to 30 days, period after which differences can be noticed between F. verticillioides and F. proliferatum.
As regard masked fumonisins, they are recovered in F. verticillioides and also F. proliferatum cultures, furthermore no synthesis is observed on cultures grown on synthetic medium, but only in those grown on maize-based substrates
How to enhance crop production and nitrogen fluxes? A result-oriented scheme to evaluate best agri-environmental measures in Veneto Region, Italy
The cost-effectiveness of adopting agri-environmental measures (AEMs) in Europe, which combine agricultural productions with reduced N losses, is debated due to poorly targeted site-specific funding that is allocated regardless of local variability. An integrated DAYCENT model-GIS platform was developed combining pedo-climatic and agricultural systems information. The aim was to evaluate best strategies to improve N fluxes of agro-ecosystems within a perspective of sustainable intensification. Indicators of agronomic efficiency and environmental quality were considered. The results showed that agronomic benefits were observed with a continuous soil cover (conservation agriculture and cover crops), which enhanced nitrogen use efficiency (+17%) and crop yields (+34%), although in some cases these might be overestimated due to modelling limitations. An overall environmental improvement was found with continuous soil cover and long-term change from mineral to organic inputs (NLeach 45 Mg ha 121), which were effective in the sandy soils of western and eastern Veneto with low SOM, improving the soil-water balance and nutrients availability over time. Results suggest that AEM subsidies should be allocated at a site-specific level that includes pedo-climatic variability, following a result-oriented approach
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