Quasi-TEM modes in rectangular waveguides: a study based on the properties of PMC and hard surfaces

Hard surfaces or magnetic surfaces can be used to propagate quasi-TEM modes inside closed waveguides. The interesting feature of these modes is an almost uniform field distribution inside the waveguide. But the mechanisms governing how these surfaces act, how they can be characterized, and further how the modes propagate are not detailed in the literature. In this paper, we try to answer these questions. We give some basic rules that govern the propagation of the quasi-TEM modes, and show that many of their characteristics (i.e. their dispersion curves) can be deduced from the simple analysis of the reflection properties of the involved surfaces

Alien Registration- Flewelling, Enoch B. (Madison, Somerset County)

https://digitalmaine.com/alien_docs/6570/thumbnail.jp

Do Beans Hurt the Soil?

You can expect a larger yield of corn following a soybean crop than if the field had been in corn the previous year with conditions as they were in 1942

Rapid Impact Assessment Matrix (RIAM) - An Analytical Tool in the Prioritization of Water Resources Management Problems in Ghana

The rapid impact assessment (RIAM), which was developed in Denmark, is a new tool for the execution of environmental impact assessments. RIAM is quite flexible, transparent and leaves a permanent record, which can be independently checked, validated or updated. RIAM has successfully been used to prioritize water resources management problems in Ghana in the order of which problems call for the most urgent attention. The priority list was easily validated and accepted to be the true reflection of the situation at a national workshop in which experts and representatives from water agencies, donor agencies, university faculties and departments, research institutes, private institutions and organizations including Non Governmental Organizations (NGOs) participated. The study has shown that RIAM, which can also be used in a developing country like Ghana, is a very useful tool in such prioritization process as has been applied in this exercise

Seasonal prevalence and distribution of ticks on the Accra Plains of Ghana and their association with dermatophilosis

The professional and scientific literature on the epidemiology, treatment and economic importance of dermatophilosis has been reviewed. Particular attention being paid to the role of ticks, especially Amblyomma variegatum in causing overt disease and tick associated losses. In addition chemical and alternate methods of tick control including the use of resistant breeds of cattle, modification of vegetation and the microclimate, the introduction of tick-resistant grasses and host vaccination against ticks are discussed.An experiment herd of 26 animals and five local herds containing 605 animals on the Coastal Plains of Ghana were studied.The seasonal abundance of ticks, their association with dermatophilosis and the systemic effects of the ticks on their hosts were investigated. Four genera, Amblyomma, Boophilus, Rhipicephalus and Hyalomma were identified on cattle, A. variegatum being the predominant tick species occurring throughout the year with peak infestations in the two rainy seasons. A highly significant positive correlation was revealed between A. variegatum and dermatophilosis in four of five local herds. Unexpectedly, a significant correlation was found between Hyalomma rufipes and dermatophilosis twice and between Rhipicephalus senegalensis and dermatophilosis once in the local herds.Clinical dermatophilosis developed two months after severe tick infestation. The immune responsiveness of tick-infested cattle was suppressed as assessed by the lymphocyte transformation test (LTT) and confirmed by [3H]-thymidine incorporation assays. Decreased lymphocyte responsiveness in the Friesian cattle coincided with peak tick levels and clinical dermatophilosis. In vitro lymphocyte responsiveness to Concanavalin A in culture medium containing foetal calf serum was suppressed by serum from cattle infested with ticks. Similarly, serum from cattle infested with ticks and infected with dermatophilosis suppressed lymphocytes derived from "clean" animals i.e. control animals treated with acaricides.Repeated experimental infections in cattle healed spontaneously in spite of the fact that the immune responses of the animals were suppressed. Resolution occurred fast after the second and third infections but not after the fourth infection which healed at the same time as the first.Cross-reaction was observed between D. congolensis and PPD. The practical significance of the observed association in relation to tuberculosis skin test is discussed.It is suggested that indigenous breeds of cattle which are more resistant to ticks and dermatophilosis be kept on the Coastal Plains of Ghana. It is also recommended that acaricides with long residual activity backed-up with long-acting oxytetracycline injectables be used during periods of high tick activity to keep tick levels at low numbers. Selective hand-dressing may then be used to treat any individual animals with large tick burdens in the dry seasons

The enigmatic core L1451-mm: a first hydrostatic core? or a hidden VeLLO?

We present the detection of a dust continuum source at 3-mm (CARMA) and 1.3-mm (SMA), and 12CO(2-1) emission (SMA) towards the L1451-mm dense core. These detections suggest a compact object and an outflow where no point source at mid-infrared wavelengths is detected using Spitzer. An upper limit for the dense core bolometric luminosity of 0.05 Lsun is obtained. By modeling the broadband SED and the continuum interferometric visibilities simultaneously, we confirm that a central source of heating is needed to explain the observations. This modeling also shows that the data can be well fitted by a dense core with a YSO and disk, or by a dense core with a central First Hydrostatic Core (FHSC). Unfortunately, we are not able to decide between these two models, which produce similar fits. We also detect 12CO(2-1) emission with red- and blue-shifted emission suggesting the presence of a slow and poorly collimated outflow, in opposition to what is usually found towards young stellar objects but in agreement with prediction from simulations of a FHSC. This presents the best candidate, so far, for a FHSC, an object that has been identified in simulations of collapsing dense cores. Whatever the true nature of the central object in L1451-mm, this core presents an excellent laboratory to study the earliest phases of low-mass star formation.Comment: 15 pages, 9 figures, emulateapj. Accepted by Ap

Availability and Utilization of e-Learning Infrastructures in Federal University Of Technology, Minna

Although the Government is committed to implementing ICT in education, the process seems to be hindered by a number of barriers hence this study investigated the availability and utilization of e – learning infrastructures in Federal University of Technology, Minna to determine the level of ICT implementation. Four research questions guided the study. The population of the study was made up of 382 students and 182 lecturers randomly selected from the four schools of the institution. Data obtained was analysed using mean and t-test. Some of the findings revealed that e- learning infrastructures are not adequate in the university for teaching and leaning and management’s efforts towards the development of Information and Communication Technology (ICT) is mainly for administrative purposes. In addition, lecturers and students both have computers and laptops and can access the internet but, they do not use them for teaching and learning. Based on the findings of the study, recommendations were made to encourage the use of e – learning infrastructures to foster teaching and learning in the university. The university should as matter of urgency organise in house training for lecturers on the use of ICT for teaching and learning. Government should release the necessary funds to enable universities put in place necessary ICT infrastructures that will facilitate teaching learning.   Keywords: e – learning, infrastructure, availability, utilization and IC

An examination of the extent of implementation of the information security system and IT audit system in Ghananian Banks

The study examined the impact of information security and information technology (IT) audit in selected banks in Ghana. The study specifically, ascertained the degree of exposure to threats, it examined the extent of implementation of information security and IT audit system in the bank to protect information from threats, determined the impact, the performance and finally identified the challenges of the banks in managing information security system. A structured questionnaire was used as the main research instrument.  Four banks were selected for the study, including two local and two foreign banks. A total of 20 employees (5 from each) were sampled from the Headquarters of each bank in Accra. Only managers, IT managers, and Risk managers were sampled. The study found that the sampled level exposure of banks to threats to information systems is low. Local banks were however more exposed to threats than foreign banks. Largely the banks managed threats to information system by implementing strategies, including having an information security policy, information security organization, asset and human resource security system, information access control IT Audit system. The performance of banks in information system was moderate. Information security and IT audit system had correlated positively to the overall performance of the banks. Availability of information security policy has significant positive impact on bank performance. The study encouraged the banks to improve upon their information security and IT audit practices to ensure improvement in the performance of the banks in information security management. Keywords: Employee, Technology, Audit,Managemen

Long-term Evolution of Protostellar and Protoplanetary Disks. I. Outbursts

As an initial investigation into the long-term evolution of protostellar disks, we explore the conditions required to explain the large outbursts of disk accretion seen in some young stellar objects. We use one-dimensional time-dependent disk models with a phenomenological treatment of the magnetorotational instability (MRI) and gravitational torques to follow disk evolution over long timescales. Comparison with our previous two-dimensional disk model calculations (Zhu et al. 2009b, Z2009b) indicates that the neglect of radial effects and two-dimensional disk structure in the one-dimensional case makes only modest differences in the results; this allows us to use the simpler models to explore parameter space efficiently. We find that the mass infall rates typically estimated for low-mass protostars generally result in AU-scale disk accretion outbursts, as predicted by our previous analysis (Zhu et al. 2009a,Z2009a). We also confirm quasi-steady accretion behavior for high mass infall rates if the values of $\alpha$-parameter for the magnetorotational instability is small, while at this high accretion rate convection from the thermal instability may lead to some variations. We further constrain the combinations of the $\alpha$-parameter and the MRI critical temperature, which can reproduce observed outburst behavior. Our results suggest that dust sublimation may be connected with full activation of the MRI. This is consistent with the idea that small dust captures ions and electrons to suppress the MRI. In a later paper we will explore both long-term outburst and disk evolution with this model, allowing for infall from protostellar envelopes with differing angular momenta.Comment: Accepted to publish in Ap

Investigating the productivity and sustainability of weathered basement aquifers in tropical Africa using numerical simulation and global sensitivity analysis

Groundwater stored in weathered basement aquifers (WBAs) is a strategic water resource. In this study, we investigate the productivity of WBAs and sustainability of groundwater abstractions using a novel process‐based stochastic modeling approach, which is applied to simulate abstractions in the Precambrian basement aquifer in Ghana. The statistical distribution of the generated synthetic yield data was found in very good agreement with observed yield data from the same Ghanaian aquifer. Further analysis provided robust insights regarding how different hydrogeological parameters of the WBA, and their interplay, control aquifer productivity and sustainability. Results indicate that 97% of the simulated abstractions could sustain the yield of a hand pump (6 L/min), approximately 30% could also sustain yields >60 L/min, while only 1% could sustain yields greater than 300 L/min. The model indicates that an aquifer transmissivity value of approximately 1.4 m2/day is required for a successful hand‐pumped borehole, while a higher yielding source (60 L/min) requires a transmissivity value of at least 9.5 m2/day. A global sensitivity analysis of 13 model input parameters shows that the thickness of the regolith and the maximum hydraulic conductivity developed at the base of the saprolite are the critical factors controlling success and sustainability for low yielding hand‐pumped boreholes. For higher yielding supplies, the net recharge, the depth to groundwater, and the aquifer extent become increasingly significant. Results from this work have important implications for the potential for increased development of groundwater from WBAs in tropical Africa