A CFD-VOF based model to address intensive photobioreactor design

The design and optimization of photobioreactors for intensive microalgal cultures are key issues to increase process performance. A model to assess the photosynthetic performance of tubular, bubble column and flat photobioreactors is presented. The model has coupled microalgal light distribution, photosynthesis kinetics and gas-liquid hydrodynamics. A lumped kinetic parameter model of photosynthetic unit (PSU) has been adopted for photosynthetic reactions. The dynamics of a microalgal cell has been described according to the gas-liquid flow of a bubble column. The flow field induced by liquid turbulence and bubbles uprising throughout the photobioreactor have been simulated with ANSYS-FLUENT. A representative domain of the flat photobioreactor has been selected by adopting proper periodic boundary conditions. Turbulence dispersion fields have been assessed by numerical simulations for several bubble size. A random-walk model developed in MATLAB has been adopted to microalgal cells to assess the irradiance experienced by the PSU-cell in the photobioreactors. The photobioreactor performances - expressed in terms of global photosynthesis rate – have been assessed. Irradiance level and biomass concentration have been changed in the range of operating conditions typically adopted for known processes

Clinical and neurophysiological effects of botulinum neurotoxin type a in chronic migraine

Chronic pain syndromes present a subversion of both functional and structural nociceptive networks. We used transcranial magnetic stimulation (TMS) to evaluate changes in cortical excitability and plasticity in patients with chronic migraine (CM) treated with botulinum neurotoxin type A (BoNT/A). We enrolled 11 patients with episodic migraine (EM) and 11 affected by CM. Baseline characteristics for both groups were recorded using single-and paired-pulse TMS protocols. The same TMS protocol was repeated in CM patients after four cycles of BoNT/A completed in one year. At baseline, compared with EM patients, patients with CM had a lower threshold in both hemispheres (right hemisphere: 46% \ub1 7.8 vs. 52% \ub1 4.28, p = 0.03; left hemisphere: 52% \ub1 4.28 vs. 53.54% \ub1 6.58, p = 0.02). In EM, paired-pulse stimulation elicited a physiologically shaped response, whereas in CM, physiological intracortical inhibition (ICI) between 1 and 3 ms intervals was absent at baseline. On the contrary, increasing intracortical facilitation (ICF) was observed for all interstimulus intervals (ISIs). In CM, cortical excitability was partially reduced after BoNT/A treatment, along with a significant decrease observed in MIDAS score (from 20.7 to 9.8; p = 0.008). The lower motor threshold in CM reflects a higher cortical hyperexcitability. The lack of physiological ICI in CM could indicate sensitisation of the trigeminovascular system. Although reduced, this type of response is still observable after treatment, despite a marked clinical improvement. Our study suggests a long-term alteration of cortical plasticity due to chronic pain

Emotionotopy in the human right temporo-parietal cortex

AbstractHumans use emotions to decipher complex cascades of internal events. However, which mechanisms link descriptions of affective states to brain activity is unclear, with evidence supporting either local or distributed processing. A biologically favorable alternative is provided by the notion of gradient, which postulates the isomorphism between functional representations of stimulus features and cortical distance. Here, we use fMRI activity evoked by an emotionally charged movie and continuous ratings of the perceived emotion intensity to reveal the topographic organization of affective states. Results show that three orthogonal and spatially overlapping gradients encode the polarity, complexity and intensity of emotional experiences in right temporo-parietal territories. The spatial arrangement of these gradients allows the brain to map a variety of affective states within a single patch of cortex. As this organization resembles how sensory regions represent psychophysical properties (e.g., retinotopy), we propose emotionotopy as a principle of emotion coding

Second Surgery in Insular Low-Grade Gliomas

Background. Given the technical difficulties, a limited number of works have been published on insular gliomas surgery and risk factors for tumor recurrence (TR) are poorly documented. Objective. The aim of the study was to determine TR in adult patients with initial diagnosis of insular Low-Grade Gliomas (LGGs) that subsequently underwent second surgery. Methods. A consecutive series of 53 patients with insular LGGs was retrospectively reviewed; 23 patients had two operations for TR. Results. At the time of second surgery, almost half of the patients had experienced progression into high-grade gliomas (HGGs). Univariate analysis showed that TR is influenced by the following: extent of resection (EOR) (P < 0.002),.VT2T1 value (P < 0.001), histological diagnosis of oligodendroglioma (P = 0.017), and mutation of IDH1 (P = 0.022). The multivariate analysis showed that EOR at first surgery was the independent predictor for TR (P] < 0.001). Conclusions. In patients with insular LGG the EOR at first surgery represents the major predictive factor for TR. At time of TR, more than 50% of cases had progressed in HGG, raising the question of the oncological management after the first surgery

Si-compatible candidates for high-K dielectrics with the Pbnm perovskite structure

We analyze both experimentally (where possible) and theoretically from first-principles the dielectric tensor components and crystal structure of five classes of Pbnm perovskites. All of these materials are believed to be stable on silicon and are therefore promising candidates for high-K dielectrics. We also analyze the structure of these materials with various simple models, decompose the lattice contribution to the dielectric tensor into force constant matrix eigenmode contributions, explore a peculiar correlation between structural and dielectric anisotropies in these compounds and give phonon frequencies and infrared activities of those modes that are infrared-active. We find that CaZrO_3, SrZrO_3, LaHoO_3, and LaYO_3 are among the most promising candidates for high-K dielectrics among the compounds we considered.Comment: 17 pages, 9 figures, 4 tables. Supplementary information: http://link.aps.org/supplemental/10.1103/PhysRevB.82.064101 or http://www.physics.rutgers.edu/~sinisa/highk/supp.pd

A new fluorescent oligonucleotide probe for in-situ identification of Microcystis aeruginosa in freshwater.

contaminated water bodies (freshwater, brackish and marine areas). Among 150 known cyanobacteria genera,>40 species are able to produce toxins, which are natural compounds that differ from both a chemical and toxicological point of view and are responsible for acute and chronic poisoning in animals and humans. Among the main classes of cyanotoxins, microcystins are frequently found in the environment. Fast and accurate methods for unequivocally identifying microcystin-producing cyanobacteria, such as Microcystis aeruginosa in water bodies, are necessary to distinguish them from other non-toxic cyanobacteria and to manage and monitor algal blooms. For this purpose, we designed, developed and validated an oligonucleotide probe for FISH (Fluorescence In Situ Hybridization) analysis to detect Microcystis aeruginosa at the species level even at relatively low concentrations in freshwater. The FISH probe, MicAerD03, was designed using the ARB software with the Silva database within the framework of the MicroCoKit project, also with the intention of adding it to the microarray from the EU project, μAQUA, for freshwater pathogens, which had only genus level probes for Microcystis. We tested various fixative methods to minimize the natural autofluorescence from chlorophyll-a and certain accessory pigments (viz., phycobilins and carotenoids). The FISH probe was tested on pure cultures of Microcystis aeruginosa, and then successfully applied to water samples collected from different sampling points of the Tiber River (Italy), using a laser confocal microscope. Subsequently, the probe was also conjugated at the 5′ end with horse-radish peroxidase (HRP-MicAerD03) to apply the CAtalysed Reported Deposition-FISH (CARD-FISH) for increasing the fluorescence signal of the mono-fluorescently labelled probe and make it possible to detect M. aeruginosa using an epifluorescence microscope. Samples taken within the EU MicroCokit project indicated thatmicroarray signals for Microcystis were coming from single cells and not colonial cells. We confirmed this with the CARD-FISH protocol used here to validate the microarray signals for Microcystis detected at the genus level in MicroCokit. This paper provides a new early warning tool for investigating M. aeruginosa at the species level even at low cell concentrations in surface water, which can be added to the μAqua microarray for all freshwater pathogens to complete the probe hierarchy for Microcystis aeruginosa

Pressure Tuning of the Charge Density Wave in the Halogen-Bridged Transition-Metal (MX) Solid Pt2Br6(NH3)4Pt_2Br_6(NH_3)_4

We report the pressure dependence up to 95 kbar of Raman active stretching modes in the quasi-one-dimensional MX chain solid $Pt_2Br_6(NH_3)_4$. The data indicate that a predicted pressure-induced insulator-to-metal transition does not occur, but are consistent with the solid undergoing either a three-dimensional structural distortion, or a transition from a charge-density wave to another broken-symmetry ground state. We show that such a transition cacan be well-modeled within a Peierls-Hubbard Hamiltonian. 1993 PACS: 71.30.+h, 71.45.Lr, 75.30.Fv, 78.30.-j, 81.40.VwComment: 4 pages, ReVTeX 3.0, figures available from the authors on request (Gary Kanner, [email protected]), to be published in Phys Rev B Rapid Commun, REVISION: minor typos corrected, LA-UR-94-246