The Random Discrete Action for 2-Dimensional Spacetime

A one-parameter family of random variables, called the Discrete Action, is defined for a 2-dimensional Lorentzian spacetime of finite volume. The single parameter is a discreteness scale. The expectation value of this Discrete Action is calculated for various regions of 2D Minkowski spacetime. When a causally convex region of 2D Minkowski spacetime is divided into subregions using null lines the mean of the Discrete Action is equal to the alternating sum of the numbers of vertices, edges and faces of the null tiling, up to corrections that tend to zero as the discreteness scale is taken to zero. This result is used to predict that the mean of the Discrete Action of the flat Lorentzian cylinder is zero up to corrections, which is verified. The ``topological'' character of the Discrete Action breaks down for causally convex regions of the flat trousers spacetime that contain the singularity and for non-causally convex rectangles.Comment: 20 pages, 10 figures, Typos correcte

Potential to Enhance the Prescribing of Generic Drugs in Patients with Mental Health Problems in Austria; Implications for the Future

Background: Scrutiny over pharmaceutical expenditure is increasing leading to multiple reforms. This includes Austria with measures to lower generic prices and enhance their utilization. However the situation for newer antidepressants and atypical antipsychotic medicines (AAPs) is different to PPIs, statins, and renin-angiotensin inhibitor drugs with greater tailoring of therapy and no wish to switch products in stable patients. Authorities welcome generics though given the high costs particularly of single-sourced AAPs. Objective: Assess (a) changes in utilization of venlafaxine versus other newer antidepressants before and after availability of generics, (b) utilization of generic versus originator venlafaxine, (c) price reductions of venlafaxine over time and their influence on total expenditure, (d) utilization of risperidone versus other AAPs, (e) suggest potential additional reforms that could be introduced if pertinent to further enhance the use of generics. Methodology: A quasi-experimental study design with a segmented time series and an observational study. Utilization measured in defined daily doses (DDDs) and total expenditure per DDD and over time. Results: No appreciable changes in the utilization of venlafaxine and risperidone after generics. The reduction in expenditure/DDD for venlafaxine decreased overall expenditure on newer antidepressants by 5% by the end of the study versus just before generics despite a 37% increase in utilization. Expenditure will further decrease if reduced prescribing of duloxetine. Conclusion: Depression, schizophrenia, and bipolar diseases are complex diseases. As a result, specific measures are needed to encourage the prescribing of generic risperidone and venlafaxine when multiple choices are appropriate. Authorities cannot rely on a “Hawthorne” effect between classes to enhance the use of generics. Measures may include prescribing restrictions for duloxetine. No specific measures planned for AAPs with more multiple-sourced AAPs becoming available

Effectiveness of method improvements to reduce variability of brood termination rate in honey bee brood studies under semi-field conditions

Quantitative assessments of adverse effects of plant protection products on honey bee brood (Apis mellifera L.) may be carried out according to the methods given by the OECD Guidance Document No. 75 (2007). In recent years a number of studies displayed a strong variability in brood termination rates, a key endpoint. Due to these variances no definite conclusions regarding potential brood effects were possible, and the studies needed to be repeated. Due to this, attempts to improve the methodology were initiated by the Working Group ‘Honey bee brood' of the German AG Bienenschutz. In 2011, honey bee brood studies adapted to these identified possible improvements resulted in better results compared to historical data. Based on the analysed results, the working group recommends to improve the method by using bigger colonies with more brood, using 4 instead of 3 replicates for better interpretation of data, starting the study early in the season, avoiding major modifications of the colonies shortly before application and using larger tunnels with effective crop areas preferably > 80 m². To carry out quicker brood cell assessments to reduce stress for the colonies, it is recommended to use digital brood assessment, which allows marking a higher number of cells (e.g. 200 to 400 cells)

The Vehicle, Fall 1991

Table of Contents ImprovisationAmy Schmitzerpage 5-6 Courthouse ClockAnthony Smithpage 7 The PaintingAngie Gallionpage 8 Empty MoonVictoria Bennettpage 9 ClarissaLaura Durnellpage 10 untitledNancy Jamespage 11 Imprisoned (photo)Dan Kooncepage 12 I Hit Mother Nature with My Ten SpeedJohn Haywardpage 13 The Realm of MotherJennifer Moropage 14-16 untitled (drawing)Mark Randallpage 20 With Purity and PerversionBret Evangelistapage 21 O\u27Hare AirportAnthony Smithpage 22 morgen, my desolationtravis mcdadepage 22-23 Ever GreenChris Rosenstockpage 24 JigsawThomas D. Schnarrepage 25-26 Notes on the Egyptian ExhibitVictoria Bennettpage 27 Moving OnChristina Roypage 28 weep my inquisitive hearttravis mcdadepage 29-30 Dance (drawing)Tim Cullotonpage 31 Roots of the OakThomas D. Schnarrepage 32-33 god\u27s suicideLiam Burkepage 34 The Poa TreeSheila Taylorpage 35https://thekeep.eiu.edu/vehicle/1056/thumbnail.jp

Shifts in Coding Properties and Maintenance of Information Transmission during Adaptation in Barrel Cortex

Neuronal responses to ongoing stimulation in many systems change over time, or “adapt.” Despite the ubiquity of adaptation, its effects on the stimulus information carried by neurons are often unknown. Here we examine how adaptation affects sensory coding in barrel cortex. We used spike-triggered covariance analysis of single-neuron responses to continuous, rapidly varying vibrissa motion stimuli, recorded in anesthetized rats. Changes in stimulus statistics induced spike rate adaptation over hundreds of milliseconds. Vibrissa motion encoding changed with adaptation as follows. In every neuron that showed rate adaptation, the input–output tuning function scaled with the changes in stimulus distribution, allowing the neurons to maintain the quantity of information conveyed about stimulus features. A single neuron that did not show rate adaptation also lacked input–output rescaling and did not maintain information across changes in stimulus statistics. Therefore, in barrel cortex, rate adaptation occurs on a slow timescale relative to the features driving spikes and is associated with gain rescaling matched to the stimulus distribution. Our results suggest that adaptation enhances tactile representations in primary somatosensory cortex, where they could directly influence perceptual decisions

Selective Reduction of AMPA Currents onto Hippocampal Interneurons Impairs Network Oscillatory Activity

Reduction of excitatory currents onto GABAergic interneurons in the forebrain results in impaired spatial working memory and altered oscillatory network patterns in the hippocampus. Whether this phenotype is caused by an alteration in hippocampal interneurons is not known because most studies employed genetic manipulations affecting several brain regions. Here we performed viral injections in genetically modified mice to ablate the GluA4 subunit of the AMPA receptor in the hippocampus (GluA4HC−/− mice), thereby selectively reducing AMPA receptor-mediated currents onto a subgroup of hippocampal interneurons expressing GluA4. This regionally selective manipulation led to a strong spatial working memory deficit while leaving reference memory unaffected. Ripples (125–250 Hz) in the CA1 region of GluA4HC−/− mice had larger amplitude, slower frequency and reduced rate of occurrence. These changes were associated with an increased firing rate of pyramidal cells during ripples. The spatial selectivity of hippocampal pyramidal cells was comparable to that of controls in many respects when assessed during open field exploration and zigzag maze running. However, GluA4 ablation caused altered modulation of firing rate by theta oscillations in both interneurons and pyramidal cells. Moreover, the correlation between the theta firing phase of pyramidal cells and position was weaker in GluA4HC−/− mice. These results establish the involvement of AMPA receptor-mediated currents onto hippocampal interneurons for ripples and theta oscillations, and highlight potential cellular and network alterations that could account for the altered working memory performance

The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements

The top-shaped morphology characteristic of asteroid (101955) Bennu, often found among fast-spinning asteroids and binary asteroid primaries, may have contributed substantially to binary asteroid formation. Yet a detailed geophysical analysis of this morphology for a fast-spinning asteroid has not been possible prior to the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of the OSIRIS-REx mission, we find a notable transition in Bennu’s surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface. As the intersection of the rotational Roche lobe with Bennu’s surface has been most recently migrating towards its equator (given Bennu’s increasing spin rate), we infer that Bennu’s surface slopes have been changing across its surface within the last million years. We also find evidence for substantial density heterogeneity within this body, suggesting that its interior is a mixture of voids and boulders. The presence of such heterogeneity and Bennu’s top shape are consistent with spin-induced failure at some point in its past, although the manner of its failure cannot yet be determined. Future measurements by the OSIRIS-REx spacecraft will provide insight into and may resolve questions regarding the formation and evolution of Bennu’s top-shape morphology and its link to the formation of binary asteroids

Evidence for widespread hydrated minerals on asteroid (101955) Bennu

Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 µm and thermal infrared spectral features that are most similar to those of aqueously altered CM-type carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of metres observed to date. In the visible and near-infrared (0.4 to 2.4 µm) Bennu’s spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth

Controlled simultaneous rotation of multiple optically trapped particles

We present a method for the controlled alignment or rotation of birefringent particles trapped in multiple optical trap sites of an interference pattern between two Laguerre-Gaussian laser modes. Controlled spin or alignment of the particles within each individual trap site is achieved independently of the lateral or rotational motion of the interference pattern as a whole. This technique may lead to driving arrays of micro-machines and micro-fluidic studies and can be used in combination with dynamically generated trapping arrays for uniformly distributed stirring throughout microscopic volumes of fluid.</p