Do Nitrogen and Phosphorus Influence Channel Catfish Growth in a Great Plains River?

Evaluating abiotic environmental factors that influence growth of sportfish is key to understanding population dynamics and making appropriate management decisions. This is especially true in river systems where primary and secondary productivity can vary across temporal and spatial scales. In this study, we assessed fish responses to ambient nutrient levels (total nitrogen and total phosphorus) using growth rates determined from age-1 Channel Catfish, Ictalurus punctatus, in Platte River, Nebraska. Water quality and growth data were collected from sites across the central and lower Platte River from 2007 to 2013. We analyzed Platte River water quality data to find yearly average levels of total nitrogen and phosphorus in the system. Results show a significant difference in growth rates and nutrients levels across Platte River segments, however nutrient levels did not help explain the differences in growth. For example, the mean growth rate across years was not significant between central and lower river segments (p-value = 0.202), but the mean total nitrogen and total phosphorus levels were significantly greater in the lower river segment across all years (p = 0.004 for nitrogen and p = 2.028-6 for phosphorus). While this study lacks evidence for a clear correlation between nutrient levels and Channel Catfish growth future investigations could help clarify the short-term and long-term impacts of eutrophication of rivers such as the Platte River that run through agricultural and urban landscpaes

The fundamental cycle of concept construction underlying various theoretical frameworks

In this paper, the development of mathematical concepts over time is considered. Particular reference is given to the shifting of attention from step-by-step procedures that are performed in time, to symbolism that can be manipulated as mental entities on paper and in the mind. The development is analysed using different theoretical perspectives, including the SOLO model and various theories of concept construction to reveal a fundamental cycle underlying the building of concepts that features widely in different ways of thinking that occurs throughout mathematical learning

Properties of L1210 cells resistant to α-difluoromethylornithine

L1210 cells were selected for resistance to the ornithine decarboxylase (ODC) inhibitor, α-difluromethylornithine. When grown in the absence of the inhibitor, these cells possessed very high ornithine decarboxylase levels. These represented about 1 part in 300 of the soluble protein, which is several hundred times greater than the maximal value found in the original L1210 cells. The resistant cells contained at least 100-fold higher levels of ODC mRNA but the half-life of ODC (about 45 min) was not altered significantly. The resistant cells had much higher putrescine and cadaverine levels than control cells, but there was no significant difference in cellular spermidine or spermine content or in production of 5'-methylthioadenosine, which is a measure of polyamine synthesis. Addition of putrescine to the control or resistant cells had no effect on their content of spermidine and spermine but addition of decarboxylated S-adenosylmethionine increased the content of spermidine and spermine. These results indicate that ornithine decarboxylase is not the rate-limiting step in polyamine synthesis in these L1210 cells. The growth of the α -difluoromethylornithine-resistant L1210 cells was inhibited when their ability to synthesize spermidine and spermine was blocked by the addition of the S-adenosylmethionine decarboxylase inhibitor, 5'-deoxy-5'-[N-methyl-N-(3-hydrazinopropyl)]aminoadenosine. Treatment with this compound produced a reduction of more than 85% in the production of 5'-methylthioadenosine and led to a large increase in the content of putrescine and a substantial decline in the content of spermidine and spermine. These results indicate the potential value of S-adenosylmethionine decarboxylase inhibitors as therapeutic agents in conditions where ODC inhibitors are ineffective

Creation of macroscopic quantum superposition states by a measurement

We propose a novel protocol for the creation of macroscopic quantum superposition (MQS) states based on a measurement of a non-monotonous function of a quantum collective variable. The main advantage of this protocol is that it does not require switching on and off nonlinear interactions in the system. We predict this protocol to allow the creation of multiatom MQS by measuring the number of atoms coherently outcoupled from a two-component (spinor) Bose-Einstein condensate.Comment: 4 pages (revtex4), 2 figure

Control of ornithine decarboxylase activity in α -difluoromethylornithine-resistant L1210 cells by polyamines and synthetic analogues

The regulation of ornithine decarboxylase (ODC) activity by the polyamine derivatives N1,N8-bis(ethyl)-spermidine and N1,N12-bis(ethyl)spermine was studied using a line of L1210 cells resistant to α -difluoromethylornithine (D-R cells), which contain very high levels of ODC, and a synthetic mRNA prepared from a plasmid containing an insert corresponding to ODC mRNA adjacent to an SP6 RNA polymerase promoter. Studies in which ODC protein was labeled in the D-R cells by exposure to [35S]methionine indicated that the polyamine derivatives and their physiological counterparts led to an increased rate of degradation of ODC and to a rapid reduction in ODC synthesis without affecting the content of ODC mRNA. Direct evidence that the polyamine derivatives act by inhibiting the translation of the ODC mRNA was obtained by studying their effects on the translation of ODC mRNA in reticulocyte lysates. This translation was strongly inhibited by the addition of N1,N8-bis(ethyl)spermidine, spermidine, N1,N12-bis(ethyl)spermine, or spermine but was not affected much by putrescine. The inhibition of the translation of ODC mRNA by either of the bis(ethyl) polyamine derivatives occurred at concentrations which stimulated total protein synthesis showing the selectivity of the reduction in ODC. The effects of polyamine derivatives and polyamines on translation of the plasmid-derived ODC mRNA were identical with those found with the D-R L1210 cell mRNA. This synthetic ODC mRNA lacks 261 bases of the 5'-leader sequences and 200 bases plus the poly(A) section from the 3'-nontranslated sequence. Therefore, these regions appear not to influence sensitivity of the ODC mRNA to inhibition of translation by polyamine derivatives

Non-deterministic Gates for Photonic Single Rail Quantum Logic

We discuss techniques for producing, manipulating and measureing qubits encoded optically as vacuum and single photon states. We show that a universal set of non-deterministic gates can be constructed using linear optics and photon counting. We investigate the efficacy of a test gate given realistic detector efficiencies.Comment: 8 pages, 6 figure

On the Spectrum of Field Quadratures for a Finite Number of Photons

The spectrum and eigenstates of any field quadrature operator restricted to a finite number $N$ of photons are studied, in terms of the Hermite polynomials. By (naturally) defining \textit{approximate} eigenstates, which represent highly localized wavefunctions with up to $N$ photons, one can arrive at an appropriate notion of limit for the spectrum of the quadrature as $N$ goes to infinity, in the sense that the limit coincides with the spectrum of the infinite-dimensional quadrature operator. In particular, this notion allows the spectra of truncated phase operators to tend to the complete unit circle, as one would expect. A regular structure for the zeros of the Christoffel-Darboux kernel is also shown.Comment: 16 pages, 11 figure