Soil Physical and Hydrological Properties, and Greenhouse Gas Emissions under Integrated Crop-Livestock Agroecosystems

Cover crops (CCs) and grazing play a critical role in successful implementation of the integrated crop-livestock system (ICLS) because they can have a direct impact on soils and greenhouse gas emissions. The objectives of this study were to (i) evaluate the short-term impacts of CCs [grass dominated cover crops (GdC) and legume dominated cover crops (LdC)] and grazed CCs and corn (Zea mays L.) residue under oat (Avena sativa L.)–CC–corn rotation on soil physical and hydrological properties; (ii) quantify the architecture of soil pores using X-ray computed tomography (CT) for soils managed under long-term ICLS, native grazed pasture and corn-soybean cropping system, and to examine relationships between CT-measured pore parameters and soil hydro-physical properties; (iii) evaluate the impact of CCs (GdC and LdC) and grazed CCs and corn residue under oats-CCs-corn rotation on soil surface carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) fluxes; and (iv) simulate water content and temperature for soils using HYDRUS model under grass dominated CC, cattle grazedgrass dominated CC and bare soils under ICLS. Cover crops reduced soil bulk density (b) and soil penetration resistance (SPR) at 0-10 and 10-20 cm depths and, in general, increased soil water retention (SWR) and total porosity compared to the no cover crops. Cattle grazing generally increased the b and SPR at both depths, however, the values of SPR did not surpass the critical values which indicated that the grazing did not have an adverse effect on soils in terms of root proliferation. Retention of water and total pore space in soil was reduced due to the grazing. Long-term ICLS enhanced CT-measured macroporosity (0.084 mm3 mm-3) and reduced b (1.18 Mg m-3) compared to the corn-soybean cropping system (0.012 mm3 mm-3; 1.51 Mg m-3). The increased proportion of pore volume contained in the largest pore cluster and higher connected porosity under long-term ICLS significantly enhanced saturated hydraulic conductivity (Ksat) of the soils compared to the corn-soybean cropping system. The GdC+G appeared to reduce cumulative CO2 (4042 kg C ha-1) and N2O (1499 g N ha-1) fluxes compared to the LdC+G (4819 kg C ha-1for CO2 and 2017 g N ha-1 for N2O), indicating the superiority of GdC+G over the LdC+G in reducing the greenhouse gas (GHG) fluxes in short-term. Cumulative CH4 flux was not affected by ICLS. The HYDRUS model was used to simulate soil water content and soil temperature from the GdC, GdC+G and no cover crop and G (NC) treatments. The model was calibrated using data from 2017 and then validated with data from 2018 growing season. The R2 and index of agreement (d) values for simulations of soil water content varied from 0.26–0.78 and 0.52–0.89, respectively during the validation period. The corresponding values for soil temperature were 0.48–0.99 and 0.80–0.99, respectively. The model performed better in simulating soil temperature compared to that of the soil water content over the study period. This study illustrates that cover cropping in shorter duration (2-3 yr) enhanced some soil physical attributes, however, grazing cover crops and crop residue had small or neutral effects on soils. The CT-study represented the benefits of long-term ICLS for maintaining or improving soil pore connectivity and other parameters critical for soil water transport. The GHG study showed that, in general, cover crops and grazing of cover crop and corn residue did not impact CO2, N2O and CH4 fluxes in short-term. Long-term studies are required to capture the influence of management practices such as ICLS on GHG fluxes. The modeling study showed that owing to the satisfactory performance of HYDRUS in simulating soil water content and temperature under ICLS, and this model can act as a promising tool in simulating the long-term benefits of conservation practices that involve diverse CCs and grazing CCs and crop residue in enhancing the soil moisture conservation. Overall, the results of this study indicate that integrating livestock grazing in the row crop rotations that involve diverse CCs can improve soil physical and hydrological properties and has a potential to mitigate greenhouse gas emissions

Vulvar malignant melanoma: a rare tumor with worse prognosis

Malignant melanoma, which has a highly malignant potential, is a tumor of the skin and mucosal membranes. Malignant melanomas of the female genital tract, including the vulva and vagina, are rare. Their overall prognosis is worse. A 75 year old woman presented with complaint of growth in vulvar region since 4 months. There was history of itching in vulvar region over growth. Surgery is still the best available treatment for the control and potential cure of malignant melanomas

Acoustic Emission Detection and Prediction of Fatigue Crack Propagation in Composite Patch Repairs using Neural Networks

An aircraft is subjected to severe structural and aerodynamic loads during its service life. These loads can cause damage or weakening of the structure especially for aging military and civilian aircraft, thereby affecting its load carrying capabilities. Hence composite patch repairs are increasingly used to repair damaged aircraft metallic structures to restore its structural efficiency. This paper presents the results of Acoustic Emission (AE) monitoring of crack propagation in 2024-T3 Clad aluminum panels repaired with adhesively bonded octagonal, single sided boron/epoxy composite patch under tension-tension fatigue loading. Crack propagation gages were used to monitor crack initiation. The identified AE sensor features were used to train neural networks for predicting crack length. The results show that AE events are correlated with crack propagation. AE system was able to detect crack propagation even at high noise condition of 10 Hz loading; that crack propagation signals can be differentiated from matrix cracking signals that take place due to fiber breakage in the composite patch. Three back-propagation cascade feed forward networks were trained to predict crack length based on the number of fatigue cycles, AE event number, and both the Fatigue Cycles and AE events, as inputs respectively. Network using both fatigue cycles and AE event number as inputs to predict crack length gave the best results, followed by Network with fatigue cycles as input, while network with just AE events as input had a greater error

Probing Non-perturbative Supersymmetry Breaking through Lattice Path Integrals

We investigate non-perturbative supersymmetry breaking in various models of quantum mechanics, including $\mathcal{PT}$-symmetric models, using lattice path integrals. These theories are discretized on a temporal Euclidean lattice with periodic or anti-periodic boundary conditions. Hamiltonian Monte Carlo algorithm is used to update the field configurations to their equilibrium values. The ratios of fermionic and bosonic mass gaps, and Ward identities are used as tools for probing supersymmetry breaking. Our simulations suggest that non-perturbative supersymmetry breaking is absent in quantum mechanics models exhibiting $\mathcal{PT}$-symmetry.Comment: v2: 24 pages; 15 figures. References update

Overview of Performance of Coding Techniques in Mobile WiMAX Based System

In this paper, we present the review of the convolution coding (CC) and convolutional product code (CPC) based on mobile WiMAX system. In coding techniques the number of symbols in the source encoded message is increased in acontrolled manner in order to facilitate two basic objectives at the receiver one is Error detection and other is Error correction. The amount of error detection and correction required and its effectiveness depends on the signal to noise ratio(SNR). The WiMAX technology based on standard 802-16 wireless MAN is configured in the same way as a traditional cellular network with base stations using point to multipoint architecture to drive a service over a radius up to several kilometers. The range and the Non Line of Sight (NLOS) ability of WiMAX make the system very attractive for users, but there will be slightly higher BER at low SNR. Coding is a technique where redundancy is added to original bit sequence to increase the reliability of the communication. This paper reviews the code used in mobile WIMAX. A detailed description of the coding techniques in WIMAX system is studied