106 research outputs found
A determinant approach for generalized -Bernoulli polynomials and asymptotic results
In earlier work, we introduced three families of polynomials where the
generating function of each set includes one of the three Jackson -analogs
of the Bessel function. This paper gives determinant representation for each
family, their large asymptotics, and two expansion theorems for specific
classes of entire functions. We include two examples
Multi-fidelity Design of Porous Microstructures for Thermofluidic Applications
As modern electronic devices are increasingly miniaturized and integrated,
their performance relies more heavily on effective thermal management.
Two-phase cooling methods enhanced by porous surfaces, which capitalize on
thin-film evaporation atop structured porous surfaces, are emerging as
potential solutions. In such porous structures, the optimum heat dissipation
capacity relies on two competing objectives that depend on mass and heat
transfer. The computational costs of evaluating these objectives, the high
dimensionality of the design space which a voxelated microstructure
representation, and the manufacturability constraints hinder the optimization
process for thermal management. We address these challenges by developing a
data-driven framework for designing optimal porous microstructures for cooling
applications. In our framework we leverage spectral density functions (SDFs) to
encode the design space via a handful of interpretable variables and, in turn,
efficiently search it. We develop physics-based formulas to quantify the
thermofluidic properties and feasibility of candidate designs via offline
simulations. To decrease the reliance on expensive simulations, we generate
multi-fidelity data and build emulators to find Pareto-optimal designs. We
apply our approach to a canonical problem on evaporator wick design and obtain
fin-like topologies in the optimal microstructures which are also
characteristics often observed in industrial applications.Comment: 24 pages, 10 figure
Probabilistic Neural Data Fusion for Learning from an Arbitrary Number of Multi-fidelity Data Sets
In many applications in engineering and sciences analysts have simultaneous
access to multiple data sources. In such cases, the overall cost of acquiring
information can be reduced via data fusion or multi-fidelity (MF) modeling
where one leverages inexpensive low-fidelity (LF) sources to reduce the
reliance on expensive high-fidelity (HF) data. In this paper, we employ neural
networks (NNs) for data fusion in scenarios where data is very scarce and
obtained from an arbitrary number of sources with varying levels of fidelity
and cost. We introduce a unique NN architecture that converts MF modeling into
a nonlinear manifold learning problem. Our NN architecture inversely learns
non-trivial (e.g., non-additive and non-hierarchical) biases of the LF sources
in an interpretable and visualizable manifold where each data source is encoded
via a low-dimensional distribution. This probabilistic manifold quantifies
model form uncertainties such that LF sources with small bias are encoded close
to the HF source. Additionally, we endow the output of our NN with a parametric
distribution not only to quantify aleatoric uncertainties, but also to
reformulate the network's loss function based on strictly proper scoring rules
which improve robustness and accuracy on unseen HF data. Through a set of
analytic and engineering examples, we demonstrate that our approach provides a
high predictive power while quantifying various sources uncertainties
Lyn Hejinian's and Charles Bernstein's language poetics : a postmodern conceptual grammar
Available from British Library Document Supply Centre- DSC:DXN058269 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Nebular Hα Limits for Fast Declining SNe Ia
One clear observational prediction of the single-degenerate progenitor scenario as the origin of type Ia supernovae (SNe) is the presence of relatively narrow (approximate to 1000 km s(-1)) H alpha emission at nebular phases, although this feature is rarely seen. We present a compilation of nebular phase H alpha limits for SN Ia in the literature and demonstrate that this heterogenous sample has been biased toward SN Ia with relatively high luminosities and slow decline rates, as parameterized by Delta m(15)(B), the difference in B-band magnitude between maximum light and 15 days afterward. Motivated by the need to explore the full parameter space of SN Ia and their subtypes, we present two new and six previously published nebular spectra of SN Ia with Delta m(15)(B) > 1.3 mag (including members of the transitional and SN1991bg-like subclasses) and measure nondetection limits of L-H alpha < 0.85-9.9 x 10(36) erg s(-1), which we confirmed by implanting simulated H alpha emission into our data. Based on the latest models of swept-up material stripped from a nondegenerate companion star, these L-H alpha values correspond to hydrogen mass limits of M-H less than or similar to 1-3 x 10(-4) M-circle dot, which are roughly three orders of magnitude below that expected for the systems modeled, although we note that no simulations of H alpha nebular emission in such weak explosions have yet been performed. Despite the recent detection of strong H alpha in ASASSN-18tb (SN 2018fhw; Delta m(15)(B) = 2.0 mag), we see no evidence that fast-declining systems are more likely to have late time H alpha emission, although a larger sample is needed to confirm this result.Korea Astronomy and Space Science Institute (Republic of Korea) [GN-2008A-Q-17, GS-2018A-Q-315]; NSF [AST-1615455, AST-1821987, 1821967, AST-1515559]; NASA grant [ADAP-80NSSC19K0578]; DIRAC Institute in the Department of Astronomy at the University of WashingtonThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Local actin nucleation tunes centrosomal microtubule nucleation during passage through mitosis
Cells going through mitosis undergo precisely timed changes in cell shape and organisation, which serve to ensure the fair partitioning of cellular components into the two daughter cells. These structural changes are driven by changes in actin filament and microtubule dynamics and organisation. While most evidence suggests that the two cytoskeletal systems are remodelled in parallel during mitosis, recent work in interphase cells has implicated the centrosome in both microtubule and actin nucleation, suggesting the potential for regulatory crosstalk between the two systems. Here, by using both in vitro and in vivo assays to study centrosomal actin nucleation as cells pass through mitosis, we show that mitotic exit is accompanied by a burst in cytoplasmic actin filament formation that depends on WASH and the Arp2/3 complex. This leads to the accumulation of actin around centrosomes as cells enter anaphase and to a corresponding reduction in the density of centrosomal microtubules. Taken together, these data suggest that the mitotic regulation of centrosomal WASH and the Arp2/3 complex controls local actin nucleation, which may function to tune the levels of centrosomal microtubules during passage through mitosis
Supernova 2018cuf : a type iip supernova with a slow fall from plateau
We present multiband photometry and spectroscopy of SN 2018cuf, a Type IIP ("P"for plateau) supernova (SN) discovered by the Distance Less Than 40 Mpc Survey within 24 hr of explosion. SN 2018cuf appears to be a typical SN IIP, with an absolute V-band magnitude of -16.73 ± 0.32 at maximum and a decline rate of 0.21 ± 0.05 mag/50 days during the plateau phase. The distance of the object was constrained to be 41.8 ± 5.7 Mpc by using the expanding photosphere method. We used spectroscopic and photometric observations from the first year after the explosion to constrain the progenitor of SN 2018cuf using both hydrodynamic light-curve modeling and late-time spectroscopic modeling. The progenitor of SN 2018cuf was most likely a red supergiant of about 14.5 Me that produced 0.04 ± 0.01 Me 56Ni during the explosion. We also found ∼0.07 Me of circumstellar material (CSM) around the progenitor is needed to fit the early light curves, where the CSM may originate from presupernova outbursts. During the plateau phase, high-velocity features at ∼11,000 km s-1 were detected in both the optical and near-infrared spectra, supporting the possibility that the ejecta were interacting with some CSM. A very shallow slope during the postplateau phase was also observed, and it is likely due to a low degree of nickel mixing or the relatively high nickel mass in the SN.Fil: Dong, Yize. University of California at Davis; Estados UnidosFil: Valenti, S.. University of California at Davis; Estados UnidosFil: Bostroem, K. A.. University of California at Davis; Estados UnidosFil: Sand, D. J.. University of Arizona; Estados UnidosFil: Andrews, Jennifer E.. University of Arizona; Estados UnidosFil: Galbany, Lluís. Universidad de Granada; EspañaFil: Jha, Saurabh W.. State University of New Jersey; Estados UnidosFil: Eweis, Youssef. State University of New Jersey; Estados UnidosFil: Kwok, Lindsey. State University of New Jersey; Estados UnidosFil: Hsiao, Eric. Florida State University; Estados UnidosFil: Davis, Scott. Florida State University; Estados UnidosFil: Brown, Peter J.. Texas A&M University; Estados UnidosFil: Kuncarayakti, H.. University of Turku; FinlandiaFil: Maeda, Keiichi. Kyoto University; JapónFil: Rho, Jeonghee. SETI Institute; Estados UnidosFil: Amaro, R. C.. University of Arizona; Estados UnidosFil: Anderson, J. P.. European Southern Observatory Chile; ChileFil: Arcavi, Iair. Universitat Tel Aviv; IsraelFil: Burke, Jamison. University of California; Estados UnidosFil: Dastidar, Raya. Aryabhatta Research Institute of observational sciences; IndiaFil: Folatelli, Gaston. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Haislip, Joshua. University of North Carolina at Chapel Hill; Estados UnidosFil: Hiramatsu, Daichi. University of California; Estados UnidosFil: Hosseinzadeh, Griffin. Harvard-Smithsonian Center for Astrophysics; Estados UnidosFil: Howell, D. Andrew. University of California; Estados UnidosFil: Jencson, J.. University of Arizona; Estados UnidosFil: Kouprianov, Vladimir. University of North Carolina at Chapel Hill; Estados UnidosFil: Lundquist, M.. University of Arizona; Estados UnidosFil: Lyman, J. D.. University of Warwick; Reino UnidoFil: McCully, Curtis. University of California; Estados Unido
Effects of Chitin and Its Derivative Chitosan on Postharvest Decay of Fruits: A Review
Considerable economic losses to harvested fruits are caused by postharvest fungal decay during transportation and storage, which can be significantly controlled by synthetic fungicides. However, considering public concern over pesticide residues in food and the environment, there is a need for safer alternatives for the control of postharvest decay to substitute synthetic fungicides. As the second most abundant biopolymer renewable source in nature, chitin and its derivative chitosan are widely used in controlling postharvest decay of fruits. This review aims to introduce the effect of chitin and chitosan on postharvest decay in fruits and the possible modes of action involved. We found most of the actions discussed in these researches rest on physiological mechanisms. All of the mechanisms are summarized to lay the groundwork for further studies which should focus on the molecular mechanisms of chitin and chitosan in controlling postharvest decay of fruits
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