A symmetric positive semi-definite matrix A is called completely positive if there exists a matrix B with nonnegative entries such that A = BB^{\top }. If B is such a matrix with a minimal number p of columns, then p is called the cp-rank of A. In this paper we develop a finite and exact algorithm to factorize any matrix A of cp-rank 3. Failure of this algorithm implies that A does not have cp-rank 3. Our motivation stems from the question if there exist three nonnegative polynomials of degree at most four that vanish at the boundary of an interval and are orthonormal with respect to a certain inner product., Jan Brandts, Michal Křížek., and Obsahuje seznam literatury
We study some classes of summing operators between spaces of integrable functions with respect to a vector measure in order to prove a factorization theorem for $1$-summing operators between Banach spaces.
The notion of β-normality was introduced and studied by Arhangel’skii, Ludwig in 2001. Recently, almost β-normal spaces, which is a simultaneous generalization of βnormal and almost normal spaces, were introduced by Das, Bhat and Tartir. We introduce a new generalization of normality, namely weak β-normality, in terms of θ-closed sets, which turns out to be a simultaneous generalization of β-normality and θ-normality. A space X is said to be weakly β-normal (wβ-normal) if for every pair of disjoint closed sets A and B out of which, one is θ-closed, there exist open sets U and V such that A ∩ U = A, B ∩ V = B and U ∩ V = ∅. It is shown that wβ-normality acts as a tool to provide factorizations of normality.
We investigate the sets of joint probability distributions that maximize the average multi-information over a collection of margins. These functionals serve as proxies for maximizing the multi-information of a set of variables or the mutual information of two subsets of variables, at a lower computation and estimation complexity. We describe the maximizers and their relations to the maximizers of the multi-information and the mutual information., Thomas Merkh and Guido Montúfar., and Obsahuje bibliografické odkazy
We report here the screening of sixteen cyanobacterial and three green algal strains from Thailand for their potential biohydrogen production. Five filamentous cyanobacterial species, namely Calothrix elenkinii, Fischerella muscicola, Nostoc calcicola, Scytonema bohneri, and Tolypothrix distorta, all possessing nitrogenase activity, showed potentially high biohydrogen production. These five strains showed higher hydrogen production in the absence than in the presence of nitrogen. In particular, F. muscicola had a 17-fold increased hydrogen production under combined nitrogen and sulfur deprived conditions. Among various sugars as a carbon source, glucose at 0.1% (w/v) gave the maximal hydrogen production of 10.9 μmol(H2) mg-1(Chl) h-1 in T. distorta grown in BG11 medium without nitrate. Increasing light intensity up to 250 μmol(photon) m-2 s-1 increased hydrogen production in F. muscicola and T. distorta. Overall results indicate that both F. muscicola and T. distorta have a high potential for hydrogen production amenable for further improvement by using molecular genetics technique., P. Yodsang, W. Raksajit, E.-M. Aro, P. Mäenpää, A. Incharoensakdi., and Obsahuje bibliografické odkazy
In many Austrian catchments in recent decades an increase in the mean annual air temperature and precipitation has been observed, but only a small change in the mean annual runoff. The main objective of this paper is (1) to analyze alterations in the performance of a conceptual hydrological model when applied in changing climate conditions and (2) to assess the factors and model parameters that control these changes. A conceptual rainfall-runoff model (the TUW model) was calibrated and validated in 213 Austrian basins from 1981–2010. The changes in the runoff model’s efficiency have been compared with changes in the mean annual precipitation and air temperature and stratified for basins with dominant snowmelt and soil moisture processes. The results indicate that while the model’s efficiency in the calibration period has not changed over the decades, the values of the model’s parameters and hence the model’s performance (i.e., the volume error and the runoff model’s efficiency) in the validation period have changed. The changes in the model’s performance are greater in basins with a dominant soil moisture regime. For these basins, the average volume error which was not used in calibration has increased from 0% (in the calibration periods 1981–1990 or 2001–2010) to 9% (validation period 2001–2010) or –8% (validation period 1981–1990), respectively. In the snow-dominated basins, the model tends to slightly underestimate runoff volumes during its calibration (average volume error = –4%), but the changes in the validation periods are very small (i.e., the changes in the volume error are typically less than 1–2%). The model calibrated in a colder decade (e.g., 1981–1990) tends to overestimate the runoff in a warmer and wetter decade (e.g., 2001–2010), particularly in flatland basins. The opposite case (i.e., the use of parameters calibrated in a warmer decade for a colder, drier decade) indicates a tendency to underestimate runoff. A multidimensional analysis by regression trees showed that the change in the simulated runoff volume is clearly related to the change in precipitation, but the relationship is not linear in flatland basins. The main controlling factor of changes in simulated runoff volumes is the magnitude of the change in precipitation for both groups of basins. For basins with a dominant snowmelt runoff regime, the controlling factors are also the wetness of the basins and the mean annual precipitation. For basins with a soil moisture regime, landcover (forest) plays an important role.
The effects of chilling treatment (4 °C) under low irradiance, LI (100 μmol m-2 s-1) and in the dark on subsequent recovery of photosynthesis in chilling-sensitive sweet pepper leaves were investigated by comparing the ratio of quantum yields of photosystem (PS) 2 and CO2 assimilation, ΦPS2/ΦCO2, measured in normal air (21 % O2, NA) and low O2-air (2% O2, LOA), and by analyzing chlorophyll (Chl) a fluorescence parameters. Chilling treatment in the dark had little effect on Fv/Fm and ΦPS2/ΦCO2, but it caused the decrease of net photosynthetic rate (PN) under saturating irradiance after 6-h chilling treatment, indicating that short-term chilling alone did not induce PS2 photoinhibition. Furthermore, photorespiration and Mehler reaction also did not obviously change during subsequent recovery after chilling stress in the dark. During chilling treatment under LI, there were obvious changes in Fv/Fm and ΦPS2/ΦCO2, determined in NA or LOA. Fv/Fm could recover fully in 4 h at 25 °C, and ΦPS2/ΦCO2 increased at the end of the treatment, as determined in both NA and LOA. During subsequent recovery, ΦPS2/ΦCO2 in LOA decreased faster than in NA. Thus the Mehler reaction might play an important role during chilling treatment under LI, and photorespiration was an important process during the subsequent recovery. The recovery of PN under saturating irradiance determined in NA and LOA took about 50 h, implying that there were some factors besides CO2 assimilation limiting the recovery of photosynthesis. From the progress of reduced P700 and the increase of the Mehler reaction during chilling under LI we propose that active oxygen species were the factors inducing PS1 photoinhibition, which prevented the recovery of photosynthesis in optimal conditions because of the slow recovery of the oxidizable P700. and X.-G. Li ... [et al.].
Inspired by the work of Sellars, Cumpa (2014, 2018) and Buonomo (2021) have argued that we can evaluate our metaphysical proposals on fundamental categories in terms of their capacity for reconciling the scientific and the manifest image of the world. This criterion of fundamentality would allow us to settle the question of which categories among those proposed in the debate—e.g., substance, structure or facts—have a better explanatory value. The aim of this essay is to argue against a central assumption of the criterion: semantic descriptivism. Specifically, I aim at showing that the criterion rests on the idea that the manifest picture is mostly a description of the world, and thus, it commits us with certain realism. Instead, I argue that at least some of the vocabulary we use to construct our manifest picture of the world, mental vocabulary, is evaluative rather than descriptive and thus creates problems in reconciling the manifest picture with scientific psychology and neurosciences. I conclude with some remarks on alternatives that could provide a way out of the fundamentality criterion.