Acousto-optical Scanning-Based High-Speed 3D Two-Photon Imaging In Vivo.

Recording of the concerted activity of neuronal assemblies and the dendritic and axonal signal integration of downstream neurons pose different challenges, preferably a single recording system should perform both operations. We present a three-dimensional (3D), high-resolution, fast, acousto-optic two-photon microscope with random-access and continuous trajectory scanning modes reaching a cubic millimeter scan range (now over 950 × 950 × 3000 μm3) which can be adapted to imaging different spatial scales. The resolution of the system allows simultaneous functional measurements in many fine neuronal processes, even in dendritic spines within a central core (>290 × 290 × 200 μm3) of the total scanned volume. Furthermore, the PSF size remained sufficiently low (PSFx < 1.9 μm, PSFz < 7.9 μm) to target individual neuronal somata in the whole scanning volume for simultaneous measurement of activity from hundreds of cells. The system contains new design concepts: it allows the acoustic frequency chirps in the deflectors to be adjusted dynamically to compensate for astigmatism and optical errors; it physically separates the z-dimension focusing and lateral scanning functions to optimize the lateral AO scanning range; it involves a custom angular compensation unit to diminish off-axis angular dispersion introduced by the AO deflectors, and it uses a high-NA, wide-field objective and high-bandwidth custom AO deflectors with large apertures. We demonstrate the use of the microscope at different spatial scales by first showing 3D optical recordings of action potential back propagation and dendritic Ca2+ spike forward propagation in long dendritic segments in vitro, at near-microsecond temporal resolution. Second, using the same microscope we show volumetric random-access Ca2+ imaging of spontaneous and visual stimulation-evoked activity from hundreds of cortical neurons in the visual cortex in vivo. The selection of active neurons in a volume that respond to a given stimulus was aided by the real-time data analysis and the 3D interactive visualization accelerated selection of regions of interest

A Modified Price-Sales Ratio: A Useful Tool For Investors?

This study compares returns for stock portfolios using low price-to-earnings, price-to-book, price-to-sales, and price-to-sales ratios modified for profitability of sales and long-term debt. Non-financial companies with fiscal years ending on December 31 were included in a sample covering a 17-year period (1988-2004). The resulting sample was sub-divided into six groups by level of market capitalization.  A 25 stock portfolio was then compiled for each of six valuation ratios at each level of market capitalization. An index portfolio was also computed for each level of market capitalization.  First, the results of this study showed that additional expected returns based on firm size, measured by the market value of equity, is found only at the micro-cap level (less than $25 million market capitalization). The index portfolios of mini-caps ($25-100 mill.), small caps ($100-500 mill.), and mid-caps ($500-$1 bill.) did not show any additional returns in comparison to the large-cap index portfolio. Second, no "value" portfolio for mid-caps provided significant returns above the index portfolio, suggesting a much greater level of market efficiency at this level of market capitalization.  Finally, the most significant findings of our study were that the portfolios constructed from low price-to-sales and modified price-to sales ratios performed as well or better than the more traditional price-to-earnings and price-to-book ratios. The price-to-sales ratio adjusted for profit margin (based on the prior three years) was statistically significant in three of six portfolios in comparison to the more traditional valuation ratios

Modality matters for the expression of inducible defenses: introducing a concept of predator modality

Background: Inducible defenses are a common and widespread form of phenotypic plasticity. A fundamental factor driving their evolution is an unpredictable and heterogeneous predation pressure. This heterogeneity is often used synonymously to quantitative changes in predation risk, depending on the abundance and impact of predators. However, differences in `modality', that is, the qualitative aspect of natural selection caused by predators, can also cause heterogeneity. For instance, predators of the small planktonic crustacean Daphnia have been divided into two functional groups of predators: vertebrates and invertebrates. Predators of both groups are known to cause different defenses, yet predators of the same group are considered to cause similar responses. In our study we question that thought and address the issue of how multiple predators affect the expression and evolution of inducible defenses. Results: We exposed D. barbata to chemical cues released by Triops cancriformis and Notonecta glauca, respectively. We found for the first time that two invertebrate predators induce different shapes of the same morphological defensive traits in Daphnia, rather than showing gradual or opposing reaction norms. Additionally, we investigated the adaptive value of those defenses in direct predation trials, pairing each morphotype (non-induced, Triops-induced, Notonecta-induced) against the other two and exposed them to one of the two predators. Interestingly, against Triops, both induced morphotypes offered equal protection. To explain this paradox we introduce a `concept of modality' in multipredator regimes. Our concept categorizes two-predator-prey systems into three major groups (functionally equivalent, functionally inverse and functionally diverse). Furthermore, the concept includes optimal responses and costs of maladaptions of prey phenotypes in environments where both predators co-occur or where they alternate. Conclusion: With D. barbata, we introduce a new multipredator-prey system with a wide array of morphological inducible defenses. Based on a `concept of modality', we give possible explanations how evolution can favor specialized defenses over a general defense. Additionally, our concept not only helps to classify different multipredator-systems, but also stresses the significance of costs of phenotype-environment mismatching in addition to classic `costs of plasticity'. With that, we suggest that `modality' matters as an important factor in understanding and explaining the evolution of inducible defenses

Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO3

The dynamical processes associated with electric field manipulation of the polarization in a ferroelectric remain largely unknown but fundamentally determine the speed and functionality of ferroelectric materials and devices. Here we apply subpicosecond duration, single-cycle terahertz pulses as an ultrafast electric field bias to prototypical BaTiO[subscript 3] ferroelectric thin films with the atomic-scale response probed by femtosecond x-ray-scattering techniques. We show that electric fields applied perpendicular to the ferroelectric polarization drive large-amplitude displacements of the titanium atoms along the ferroelectric polarization axis, comparable to that of the built-in displacements associated with the intrinsic polarization and incoherent across unit cells. This effect is associated with a dynamic rotation of the ferroelectric polarization switching on and then off on picosecond time scales. These transient polarization modulations are followed by long-lived vibrational heating effects driven by resonant excitation of the ferroelectric soft mode, as reflected in changes in the c-axis tetragonality. The ultrafast structural characterization described here enables a direct comparison with first-principles-based molecular-dynamics simulations, with good agreement obtained

Thoughts of Death Modulate Psychophysical and Cortical Responses to Threatening Stimuli

Existential social psychology studies show that awareness of one's eventual death profoundly influences human cognition and behaviour by inducing defensive reactions against end-of-life related anxiety. Much less is known about the impact of reminders of mortality on brain activity. Therefore we explored whether reminders of mortality influence subjective ratings of intensity and threat of auditory and painful thermal stimuli and the associated electroencephalographic activity. Moreover, we explored whether personality and demographics modulate psychophysical and neural changes related to mortality salience (MS). Following MS induction, a specific increase in ratings of intensity and threat was found for both nociceptive and auditory stimuli. While MS did not have any specific effect on nociceptive and auditory evoked potentials, larger amplitude of theta oscillatory activity related to thermal nociceptive activity was found after thoughts of death were induced. MS thus exerted a top-down modulation on theta electroencephalographic oscillatory amplitude, specifically for brain activity triggered by painful thermal stimuli. This effect was higher in participants reporting higher threat perception, suggesting that inducing a death-related mind-set may have an influence on body-defence related somatosensory representations

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

Despite evidence of West Nile virus (WNV) activity in Colombia, Venezuela and Argentina, this virus has not been reported in most South American countries. In February 2009, we commenced an investigation for WNV in mosquitoes, horses and caimans from the Pantanal, Central-West Brazil. The sera of 168 horses and 30 caimans were initially tested using a flaviviruses-specific epitope-blocking enzyme-linked immunosorbent assay (blocking ELISA) for the detection of flavivirus-reactive antibodies. The seropositive samples were further tested using a plaque-reduction neutralisation test (PRNT90) for WNV and its most closely-related flaviviruses that circulate in Brazil to confirm the detection of specific virus-neutralising antibodies. Of the 93 (55.4%) blocking ELISA-seropositive horse serum samples, five (3%) were seropositive for WNV, nine (5.4%) were seropositive for St. Louis encephalitis virus, 18 (10.7%) were seropositive for Ilheus virus, three (1.8%) were seropositive for Cacipacore virus and none were seropositive for Rocio virus using PRNT90, with a criteria of > four-fold antibody titre difference. All caimans were negative for flaviviruses-specific antibodies using the blocking ELISA. No virus genome was detected from caiman blood or mosquito samples. The present study is the first report of confirmed serological evidence of WNV activity in Brazil

Analyse et prevention des troubles du cycle reproductif chez les caprins en region semi-aride dans le Nordeste bresilien.

Une enquete ecopathologique sur les avortements caprins en elevage traditionnel dans le nord-est du Bresil a permis de mettre en evidence une succession de troubles du cycle reproductif affectant le rendement zootechnique. L'analyse du cycle a fourni les elements necessaires a la formulation de mesures de prevention de ces troubles. Il s'agit, en manipulant le cycle reproductif, de realiser une meilleure adequation entre l'offre alimentaire, tres saisonnee, et la période de mises bas. Certaines mesures de conduite de la mise bas devraient entrainer une diminution importante de la mortalite des jeunes

Comprendre et agir sur les avortements en elevage caprin: premier bilan et perspectives d'une etude ecopathologique conduite dans une petite region du Nordeste bresilien.

L'étude du probiéme des avortements des chévres constitue dans ce programme un théme de recherche appliquée dont /'objectif est de proposer rapidement des solutions techniques susceptibles d'en diminuer /'incidence. Ces conditions ont guidé le choix de Ia méthoeJologie employée