Spatial Dimensions of US Crop Selection: Recent Responses to Markets and Policy

We explicitly measure corn acreage response to the biofuels boom from 2006 to 2010. Specifically, we use newly available micro-scale planting data over time to test whether corn cultivation intensifies in proportion to the proximity of ethanol processors. We control for the endogeneity of plant location to corn acreage by using transportation network data for instruments. Our results show that reducing the distance between a farm and an ethanol plant by one percent increases acreage in corn by 0.64% and reveal a price elasticity of supply of 0.47%. To our knowledge, this is the first study that measures changes in location and intensity of corn planting in response to incentives posed by the recent biofuels boom. The results can serve as a springboard for researchers and policy-makers concerned with crop diversity, environmental sustainability, and greenhouse gas emissions.corn acreage, ethanol, panel data analysis, instrumental variables, Agricultural and Food Policy, Crop Production/Industries, Land Economics/Use, Q1, Q28, C33,

Monolithic beam to external column joints in reinforced concrete

The benefits of high strength concrete (HSC) in the construction of multi-storey buildings are commonly acknowledged. Past researchers have investigated the suitability of design codes for the use of HSC [1]. However, there are concerns about the shear behaviour of HSC beams and BCJ used in the construction of these buildings. HSC beams have equal or less shear resistance compared to normal strength concrete (NSC) beams [2], and the brittleness of HSC material could be unsuitable for BCJ as confinement stirrups may not be as effective as NSC in the column due to a smaller Poisson’s ratio. This research investigates the behaviour of HSC beams, BCJ and transfer beam column joints (TBCJ), and develop appropriate design modifications to improve their shear capacity. HSC beams were strengthened with horizontal web bars (HWB), while TBCJ were strengthened with central vertical bars (CVB). Finite element (FE) models were developed for these structures and the numerical results were compared with those of the published experimental results, concluding that good agreement had been achieved. Beam span/depth (a/d) ratio of 1.5≤a/d ≤3.02 and BCJ of beam to column depth ( db/dc ) ratio of 1.33 ≤ db/dc ≤3.1 were analysed. The FE models were compared with published test results and further ones were developed to carry out various parametric investigations. Struts and ties were mechanically modelled for beams with HWB and for TBCJ with CVB are used to recommend design equation modifications for the design of HSC beams with HWB and TBCJ with CVB. It was found that HWB and CVB are effective in beams and BCJ only with HSC as they have little influence when they were used with NSC. Using HWB in HSC beams and CVB in HSC TBCJ improved the shear capacity of these structures by 130% and 31% respectively. 1 - Regan, P. E., Kennedy -Reid I. L., Pullen, A. D., Smith, D. A. ‘The influence of aggregate type on the shear resistance of reinforced concrete’ – The Structural Engineer. 6 December 2005. p 27-32. 2 - Al-Hussaini, A. Motamed, J. ‘HSC beams with combination of links and horizontal web steel as alternative shear reinforcement’. 6th International Symposium on Utilization of High Strength/High Performance Concrete, Leipzig, June 2002. p 611- 61

Shear design of HSC beams with combination of links and horizontal web steel

The existing recommendations in Eurocode 2 and the British Code of Practice for the shear design of beams are derived from research conducted essentially on normal-strength concrete (NSC) with cube strengths up to 50 MPa, and it was found that the shear strengths of high-strength concrete (HSC) members made with limestone aggregate are below the characteristic resistances of identical NSC members. Previous experimental tests have also shown that significant differences exist in the angle of crack of shear failure of NSC and HSC. This paper presents data from five beam tests, which demonstrate that HSC with limestone aggregate has a reduced shear strength compared with NSC made with gravel and thus shows a gap in knowledge in the design approach to shear resistance of HSC beams. Previous investigations have suggested that horizontal web steels can contribute to the overall shear resistance of a reinforced concrete member in conjunction with the other constituents, concrete, tension and shear steel. The paper also presents data from tests on 11 beam tests and shows that the shear resistance of HSC beams is highly dependent on dowel action resulting from horizontal web bars positioned at the centre of the depth of the beam. Past attempts to quantify this dowel action are investigated and an improved design rule is proposed

Fruit and Vegetable Planting Restrictions: Do U.S. Farmers Even Notice?

Crop Production/Industries, Food Consumption/Nutrition/Food Safety,

Volatile composition of the peel and leaf essential oils of Citrus nobilis Lour. var deliciosa Swingle

The fruits and leaves of Citrus nobilis Lour. var deliciosa Swingle were collected from south of Iran and their essential oils were analysed by gas chromatography-mass spectrophotometry (GC-MS). The oil yields of the fresh peel and leaves obtained separately by hydrodistillation were 1.2 and 0.2% (V/W), respectively. 17 components accounting for 99.2% of the peel oil and 34 components accounting for 98.5% of the leaf oil were identified. The main classes of compounds were found to be monoterpenes [monoterpene hydrocarbons (96.0%) and monoterpene alcohols (1.8%)] in the peel oil and monoterpenes [monoterpene hydrocarbons (47.6%), monoterpene alcohols (36.9%)] and sesquiterpenes [sesquiterpene hydrocarbons (2.9%) and sesquiterpene alcohols (3.7%)] in the leaf oil. The major constituent of the peel oil were limonene (87.8%) and γ-terpinene (6.1%), while the major constituents of the leaf oil were linalool (32.8%), sabinene (28.8), (E)-β-ocimene (6.2%) and limonene (5.2%).Key words: Citrus nobilis Lour., chemical composition, essential oils, class composition

Finite difference schemes for second order systems describing black holes

In the harmonic description of general relativity, the principle part of Einstein's equations reduces to 10 curved space wave equations for the componenets of the space-time metric. We present theorems regarding the stability of several evolution-boundary algorithms for such equations when treated in second order differential form. The theorems apply to a model black hole space-time consisting of a spacelike inner boundary excising the singularity, a timelike outer boundary and a horizon in between. These algorithms are implemented as stable, convergent numerical codes and their performance is compared in a 2-dimensional excision problem.Comment: 19 pages, 9 figure

Updating a reference image for detecting motion in urban scenes

We present in this paper a construction and updating method of a reference image for motion detection in an urban environment . The proposed detection algorithm exploits differences between static edges of the scene and edges extracted from each imag e of the sequence . It allows to detect moving objects contours and moving areas contours if the background is not uniform . Th e reference image, robustly controlled, contains spatio temporal information of a great number of successive images . Updated locally with a recursive filter, it allows to integrate, after a controlled time, objects that stop in the scene . This kind of updating permits to automatically adapt with unpredictible movements of deformable or rigid objects (changes in speed and direction) . I n addition, analyzing edges allows to take into account global illumination changes and heterogeneity of the scene background i n an urban environment . This approach gives good results on complex outdoor image sequences .Nous présentons dans cet article une méthode de construction et de mise à jour d'une image de référence pour la détection du mouvement dans une scène urbaine. L'algorithme de détection proposé exploite les différences entre les contours statiques contenus dans la scène et les contours extraits de chaque image de la séquence. Il permet de mettre en évidence les contours des objets mobiles et les contours des zones affectées par le mouvement dans le cas où le fond n'est pas uniforme. L'image de référence, contrôlée de manière robuste, englobe les informations spatiales et temporelles contenues dans un grand nombre d'images successives de la séquence. Actualisée localement par l'intermédiaire d'un filtre récursif, elle permet d'intégrer, après un temps contrôlé, les objets qui s'arrêtent dans la scène. Ce type de réactualisation permet de s'adapter aux mouvements imprévisibles des objets (changement de vitesse et de direction) déformables ou non. De plus, l'analyse des contours a permis de s'affranchir des variations globales de l'éclairage ainsi que de l'hétérogénéité des fonds de la scène en milieu urbain. Cette approche obtient des résultats satisfaisants sur des images de scènes d'extérieur complexes

A posteriori error analysis and adaptive non-intrusive numerical schemes for systems of random conservation laws

In this article we consider one-dimensional random systems of hyperbolic conservation laws. We first establish existence and uniqueness of random entropy admissible solutions for initial value problems of conservation laws which involve random initial data and random flux functions. Based on these results we present an a posteriori error analysis for a numerical approximation of the random entropy admissible solution. For the stochastic discretization, we consider a non-intrusive approach, the Stochastic Collocation method. The spatio-temporal discretization relies on the Runge--Kutta Discontinuous Galerkin method. We derive the a posteriori estimator using continuous reconstructions of the discrete solution. Combined with the relative entropy stability framework this yields computable error bounds for the entire space-stochastic discretization error. The estimator admits a splitting into a stochastic and a deterministic (space-time) part, allowing for a novel residual-based space-stochastic adaptive mesh refinement algorithm. We conclude with various numerical examples investigating the scaling properties of the residuals and illustrating the efficiency of the proposed adaptive algorithm

Rituximab and risk of COVID-19 infection and its severity in patients with MS and NMOSD

Background: Choosing a safe disease modifying therapy during the COVID-19 pandemic is challenging. This case series study was conducted to determine the incidence rate and the course of Covid-19 infection in MS/NMOSD patients treated with Rituximab. Methods: In this study, we designed a web-based questionnaire. Baseline information such as patient- reported walking disability, total number of Rituximab infusions received, delayed injections, occurrence of any relapse, and the use of corticosteroids during the pandemic were collected. Also, information regarding the Covid-19 pandemic such as adherence to self-isolation, any recent exposure to an infected individual and the presence of suggestive symptoms were collected. In case of positive test results, patients were grouped into 2 categories; mild to moderate and seriously ill and outcomes were evaluated as favorable (improved/ discharged) and unfavorable (expired). Results: Two hundred fifty-eight patients with Multiple Sclerosis were enrolled in this study, 9 of the subjects (3.4) were confirmed positive for Covid-19, five of which required hospitalizations (55.5), two patients required ICU admission (22.2) and 2 two patients died (22.2). None of these patients ever mentioned using corticosteroids during the pandemic. In comparison to MS patients who were not receiving disease modifying therapy (DMT), our study indicated a higher incidence of Covid-19 infection, higher ratio of serious illness and a higher fatality ratio. Conclusions: Rituximab seems not to be safe enough during the pandemic. © 2021, The Author(s)