Hydrodynamic mixing model applied to a continuous stirred-tank reactor with and without second-order reaction

Paper 1: A hydrodynamic mixing (HDM) model, used to calculate the steady-state spatial distribution of conversion for a second-order reaction in a continuous stirred-tank reactor (CSTR) for non-premixed reactants was developed and contrasted with other methods. The HDM model is based on a segmental description of the reactor and includes turbulent mixing effects in each segment. As a test of the model, the experimental results obtained from a tubular reactor were found to be very well represented for a range of reactant ratios. Spatial distributions of concentration and segregation intensity (degree of mixing) within the CSTR were determined for a variety of reactor operating conditions for an isothermal reactor and, in addition, the spatial distribution of temperature was calculated for a non-isothermal reactor. That extension of the model was simple and straight-forward, since distributions of conversion were already available from the main model --Abstract, page 2. Paper 2: The time-varying response of an incompletely mixed continuous stirred-tank reactor (CSTR) with second-order reaction is described by an extension of the hydrodynamic mixing (HDM) model. It generates the spatial time responses of concentration and segregation intensity which result from variations in impeller speed or reactant feed rates of non-premixed feeds. These responses were determined at various levels of feed rate, reaction rate constant, and impeller speed. The validity of the HDM model for mixing alone was established by comparison with experimental data. The time-varying HDM model is based on a segmented description of the mixer-reactor and includes turbulent mixing effects within each segment. The advantages over simplified models are demonstrated by comparison of HDM model responses with responses obtained from a segmented model with segregation effects suppressed and from models based on perfect back-mixing --Abstract, page 69

Word Adjacency Graph Modeling: Separating Signal From Noise in Big Data

There is a need to develop methods to analyze Big Data to inform patient-centered interventions for better health outcomes. The purpose of this study was to develop and test a method to explore Big Data to describe salient health concerns of people with epilepsy. Specifically, we used Word Adjacency Graph modeling to explore a data set containing 1.9 billion anonymous text queries submitted to the ChaCha question and answer service to (a) detect clusters of epilepsy-related topics, and (b) visualize the range of epilepsy-related topics and their mutual proximity to uncover the breadth and depth of particular topics and groups of users. Applied to a large, complex data set, this method successfully identified clusters of epilepsy-related topics while allowing for separation of potentially non-relevant topics. The method can be used to identify patient-driven research questions from large social media data sets and results can inform the development of patient-centered interventions

Evidence for an Additional Heat Source in the Warm Ionized Medium of Galaxies

Spatial variations of the [S II]/H-Alpha and [N II]/H-Alpha line intensity ratios observed in the gaseous halo of the Milky Way and other galaxies are inconsistent with pure photoionization models. They appear to require a supplemental heating mechanism that increases the electron temperature at low densities n_e. This would imply that in addition to photoionization, which has a heating rate per unit volume proportional to n_e^2, there is another source of heat with a rate per unit volume proportional to a lower power of n_e. One possible mechanism is the dissipation of interstellar plasma turbulence, which according to Minter & Spangler (1997) heats the ionized interstellar medium in the Milky Way at a rate ~ 1x10^-25 n_e ergs cm^-3 s^-1. If such a source were present, it would dominate over photoionization heating in regions where n_e < 0.1 cm^-3, producing the observed increases in the [S II]/H-Alpha and [N II]/H-Alpha intensity ratios at large distances from the galactic midplane, as well as accounting for the constancy of [S II]/[N II], which is not explained by pure photoionization. Other supplemental heating sources, such as magnetic reconnection, cosmic rays, or photoelectric emission from small grains, could also account for these observations, provided they supply to the warm ionized medium ~ 10^-5 ergs s^-1 per cm^2 of Galactic disk.Comment: 10 pages, 1 figur

Boundedness properties of fermionic operators

The fermionic second quantization operator $d\Gamma(B)$ is shown to be bounded by a power $N^{s/2}$ of the number operator $N$ given that the operator $B$ belongs to the $r$-th von Neumann-Schatten class, $s=2(r-1)/r$. Conversely, number operator estimates for $d\Gamma(B)$ imply von Neumann-Schatten conditions on $B$. Quadratic creation and annihilation operators are treated as well.Comment: 15 page

Oral Endocrine Therapy Nonadherence, Adverse Effects, Decisional Support, and Decisional Needs in Women With Breast Cancer

BACKGROUND: Oral endocrine therapy (OET) such as tamoxifen or aromatase inhibitors reduces recurrence and mortality for the 75% of breast cancer survivors (BCSs) with a diagnosis of estrogen receptor-positive breast cancer. Because many BCSs decide not take OET as recommended because of adverse effects, understanding BCSs' decisional supports and needs is foundational to supporting quality OET decision making about whether to adhere to OET. OBJECTIVE: The aim of this study was to examine literature pertaining to OET nonadherence and adverse effects using the Ottawa Decision Support Framework categories of decisional supports and decisional needs because these factors potentially influence OET use. METHODS: A systematic literature search was performed in PubMed and CINAHL using combined search terms "aromatase inhibitors and adherence" and "tamoxifen and adherence." Studies that did not meet criteria were excluded. Relevant data from 25 publications were extracted into tables and reviewed by 2 authors. RESULTS: Findings identified the impact of adverse effects on OET nonadherence, an absence of decisional supports provided to or available for BCSs who are experiencing OET adverse effects, and the likelihood of unmet decisional needs related to OET. CONCLUSIONS: Adverse effects contribute to BCSs decisions to stop OET, yet there has been little investigation of the process through which that occurs. This review serves as a call to action for providers to provide support to BCSs experiencing OET adverse effects and facing decisions related to nonadherence. IMPLICATIONS FOR PRACTICE: Findings suggest BCSs prescribed OET have unmet decisional needs, and more decisional supports are needed for BCSs experiencing OET adverse effects

Controlled complete suppression of single-atom inelastic spin and orbital cotunnelling

The inelastic portion of the tunnel current through an individual magnetic atom grants unique access to read out and change the atom's spin state, but it also provides a path for spontaneous relaxation and decoherence. Controlled closure of the inelastic channel would allow for the latter to be switched off at will, paving the way to coherent spin manipulation in single atoms. Here we demonstrate complete closure of the inelastic channels for both spin and orbital transitions due to a controlled geometric modification of the atom's environment, using scanning tunnelling microscopy (STM). The observed suppression of the excitation signal, which occurs for Co atoms assembled into chain on a Cu$_2$N substrate, indicates a structural transition affecting the d$_z$$^2$ orbital, effectively cutting off the STM tip from the spin-flip cotunnelling path.Comment: 4 figures plus 4 supplementary figure

WHAM Observations of H-Alpha, [S II], and [N II] toward the Orion and Perseus Arms: Probing the Physical Conditions of the Warm Ionized Medium

A large portion of the Galaxy (l = 123 deg to 164 deg, b = -6 deg to -35 deg), which samples regions of the Local (Orion) spiral arm and the more distant Perseus arm, has been mapped with the Wisconsin H-Alpha Mapper (WHAM) in the H-Alpha, [S II] 6716, and [N II] 6583 lines. Several trends noticed in emission-line investigations of diffuse gas in other galaxies are confirmed in the Milky Way and extended to much fainter emission. We find that the [S II]/H-Alpha and [N II]/H-Alpha ratios increase as absolute H-Alpha intensities decrease. For the more distant Perseus arm emission, the increase in these ratios is a strong function of Galactic latitude and thus, of height above the Galactic plane. The [S II]/[N II] ratio is relatively independent of H-Alpha intensity. Scatter in this ratio appears to be physically significant, and maps of it suggest regions with similar ratios are spatially correlated. The Perseus arm [S II]/[N II] ratio is systematically lower than Local emission by 10%-20%. With [S II]/[N II] fairly constant over a large range of H-Alpha intensities, the increase of [S II]/H-Alpha and [N II]/H-Alpha with |z| seems to reflect an increase in temperature. Such an interpretation allows us to estimate the temperature and ionization conditions in our large sample of observations. We find that WIM temperatures range from 6,000 K to 9,000 K with temperature increasing from bright to faint H-Alpha emission (low to high [S II]/H-Alpha and [N II]/H-Alpha) respectively. Changes in [S II]/[N II] appear to reflect changes in the local ionization conditions (e.g. the S+/S++ ratio). We also measure the electron scale height in the Perseus arm to be 1.0+/-0.1 kpc, confirming earlier, less accurate determinations.Comment: 28 pages, 10 figures. Figures 2 and 3 are full color--GIFs provided here, original PS figures at link below. Accepted for publication in ApJ. More information about the WHAM project can be found at http://www.astro.wisc.edu/wham/ . REVISION: Figure 6, bottom panel now contains the proper points. No other changes have been mad

Testing for biogeographic mechanisms promoting divergence in Caribbean crickets (genus Amphiacusta )

This work examines whether the history of diversification of Amphiacusta (Orthoptera, Gryllidae) in the Caribbean corresponds to a vicariant or a dispersalist model.The Greater Antillean islands of the Caribbean region.The phylogenetic relationships among species were estimated using a procedure that directly estimates the underlying species tree from independent loci (in this case, one mitochondrial and one nuclear locus). This tree was then used to test for topological congruence with a vicariant model, and to estimate divergence times.The analyses based on the expected pattern of species divergence (i.e. species-tree topology) support a vicariant model. With the notable exception of a dispersal event marking the colonization of Jamaica, the timing of the events are generally consistent with a vicariant scenario, given the current taxon sampling and potential errors with dating the divergence events.The tendency of species to co-segregate by island suggests that intra-island diversification is common. Despite their flightlessness, species of Amphiacusta are apparently capable of long-distance dispersal, such as colonization from the Puerto Rican/Virgin Island bank to Jamaica. The topology of the species tree is consistent with a vicariant model of divergence, and the dates of divergence between island groups are generally consistent with an island–island vicariance model. A strict island–island vicariance scenario can, however, be rejected because of inferred dispersal events such as the colonization of Jamaica. Nevertheless, the biogeographic tests suggest that most of the diversity was generated under a combination of intra-island diversification and island–island vicariance. Additional sampling of taxa will be needed to verify this hypothesized scenario. Our findings indicate that Amphiacusta presents an ideal opportunity for examining the role of sexual selection in promoting diversification, which would complement the large number of studies focused on adaptive divergence of Caribbean taxa.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79301/1/j.1365-2699.2009.02231.x.pd