486 research outputs found
In-field soil fertility assessment of Ramat Polytechnic farm Maiduguri in North-Eastern Nigeria
In-field soil fertility valuation is an important diagnostic tool for determining the nutrient needs of plants. The main objective was to determine soil chemical characteristics. Twenty samples covering 2.5 hectares of the farm from 0-30 cm depth (< 2mm fraction) processed and analysed in the laboratory. The soils are in a state of equilibrium from the C: N ratio (14.50 to 35.00), influencing the biogeochemistry of carbon, nitrogen, and phosphorus in pedogenetic development. There was high exchangeable calcium (6.20 Cmolkg-1 to 12.40 Cmolkg-1) and magnesium (1.00Cmolkg-1 to 4.80Cmolkg-1). Potassium contents were found to be medium to high (0.27 Cmolkg-1 to 1.54 Cmolkg-1). Available phosphorus ranged from low to medium contents (1.40 mkg-1 to 22.05 mkg-1) in all the samples. Cation exchange capacity (CEC) ranged from 10.01 Cmolkg-1 to 0.41 Cmolkg-1 and percent base saturation was high having >80%. Parent materials (sedimentary deposits) had influenced the availability of phosphorus and the exchangeable bases on the farm. These findings conclude that the soils have a high fertility status. However, there are slight hazards of salinity
Quantitative Assessment of Land Cover Sensitivity to Desertification in Maigatari Local Government Area, Jigawa State, Nigeria
Desertification alludes to land degradation in arid, semi-arid and sub-humid regions resulting from various variables, counting climatic variations and human activities. When land degradation transpire within the worldâs drylands. It regularly makes desert-like conditions. Land degradation occurs all over, but is characterized as desertification when it occurs within the drylands. The study employed adjusted MEDALUS methodology using eleven indicators rainfall, evapotranspiration, aridity, soil texture, soil depth, slope gradient, drainage density, plant cover, erosion protection, sensitivity desertification index and Normalized Difference Vegetation Index (NDVI). Remote Sensing and GIS were the main techniques used in the indices computations and mapping. Thus, Shuttle Rader Topographic Map (SRTM) and Landsat 8 satellite imagery for the year 2019 with 30 meter resolution, captured in the month of August (rainy season), covering the study area were acquired from Global Land cover Facility (GLCF) University of Maryland. The study finds that the duration and intensity of rainfall is declining especially at the edge of the desert, extreme north and western part of the area. Rain quickly drained through infiltration and surface runoff which carried the little nutrients attached to the soil. Rainfall and climate is of arid type recording about 300-400mm of rainfall and the soil is low in organic matter content making it weak and less fertile and support only the cultivation of cereals and legumes. The study recommends that there is need to strengthen the laws and policies in controlling desertification and land degradation, establishment of shelterbelts to control desertification and act also as wind breakers and encourage the use of modern techniques such as drip irrigation to check the rate of infiltration and runoff.
Keyword: Desertification; Sensitivity; MEDALUS; GIS; Maigatar
Evaluation of an Internet Document Delivery Service
An Internet-based Document Delivery Service (DDS) has been developed within the framework of the CNR ( the Italian Research National Council) Project BiblioMIME, in order to take advantage of new Internet technologies and promote cooperation among CNR and Italian university libraries. Adopting such technologies changes the traditional organisation of DDS and may drastically reduce costs and delivery times. An information system managing DDS requests and monitoring the temporal evolution of the service has been implemented, running on the local-area network of a test-site library. It aims to track number and types of documents requested and received, user distribution, delivery times and types (surface mail, fax, Internet), to automate repetitive manual procedures and to deal with the various accounting methods used by other libraries. Transmission of documents is carried out by means of an e-mail/Web gateway system supporting document exchange via Internet, which assists receiving libraries in retrieving requested documents. This paper describes the architecture and main design features of the e-mail/Web gateway server (the BiblioMime server). This approach permits librarians to continue using e-mail service to send large documents, while resolving problems that users may encounter when downloading large size files with e-mail agents. The library operator sends the document as an attachment to the destination address; on fly the e-mail server extracts and saves the attachments in a web-server disk file and substitutes them with a new message part that includes an URL pointing to the saved document. The receiver can download these large objects by means of a user-friendly browser. We further discuss the data gathered during the triennium 1998-2000; this consists of about 5,000 DDS transactions per annum with 300 other Italian scientific and bio-medical libraries and commercial document suppliers. Use of the instruments described above allowed us to evaluate the performance of service "before" and "after" the use of Internet Document Delivery and to extract some critical data regarding DDS. Those include: a) libraries with which we have greater numbers of exchanges and their turnaround times; b) extraordinary reduction in costs and delivery times; c) the most frequently requested serial titles (allowing cost-effective decisions on new subscriptions); d) impact on DDS of library participation in consortia which allow user access to greater numbers of online serials
Elevated extracellular potassium ion concentrations suppress hippocampal oscillations in a mouse model of Dravet syndrome in-vitro
Background: Hippocampal hyperexcitability and seizure-like events have been consistently demonstrated in hippocampal slice preparations perfused with â„ 5 mM high [K+] artificial cerebrospinal fluid (ACSF). Accordingly, high [K+] ACSF has been effectively employed as ionic model of seizure for in vitro experiments, but then, how reliable is this model when employed for in-vitro studies of brain tissues with dysregulated K+ homeostasis? To address this question, we examined how elevations of [K+]o affect hippocampal oscillations in Scn1a mutant mouse, a mouse model of Dravet syndrome, a devastating genetic-epilepsy associated with gliosis, a major cause of dysregulated K+ homeostasis in epileptic brain.Methods: To this end, performing local field potential (LFP) recordings from hippocampi of P30 to P38 Scn1a mutant mice (Scn1a +/-) and wild-type littermates (Scn1a +/+), maintained on a C57BL/6 genetic background, in brain slice preparations in normal and high K+ conditions, we studied the effect of 4 mM and 5 mM high [K+] ACSF(s) on hippocampal oscillations.Results:Â Hippocampal hyperexcitability was observed only in Scn1a +/+ but not in Scn1a +/- mice. In Scn1a +/- mice, spontaneous hippocampal hyperexcitability was observed in normal ACSF but was significantly suppressed by 4 mM and 5 mM high [K+] ACSF(s).Conclusion: In conclusion, these findings, for the first time, provide evidence of spontaneous hippocampal activity in Scn1a+/- mice older than P30 which may be potentially used as a target for screening anti-epileptic approaches, beneficial for the treatment of DS. Elevated [K+]o-induced depolarization block of neuronal action potentials is involved in epileptic brain tissues modulated in elevated [K+]o. This mechanism underlies the suppressing effect of high [K+] ACSF on hippocampal oscillations in Scn1a+/- mice in vitro. Future studies employing the high K+ ionic model for studies of epileptic brain tissues are required to determine how K+ homeostasis is handled by neurons and glial cells in epileptic brain tissues.Keywords: Dravet syndrome, artificial cerebrospinal fluid (ACSF), Scn1a mutant mouse, depolarization bloc
Simulation and performance of an artificial retina for 40 MHz track reconstruction
We present the results of a detailed simulation of the artificial retina
pattern-recognition algorithm, designed to reconstruct events with hundreds of
charged-particle tracks in pixel and silicon detectors at LHCb with LHC
crossing frequency of . Performances of the artificial retina
algorithm are assessed using the official Monte Carlo samples of the LHCb
experiment. We found performances for the retina pattern-recognition algorithm
comparable with the full LHCb reconstruction algorithm.Comment: Final draft of WIT proceedings modified according to JINST referee's
comment
The artificial retina for track reconstruction at the LHC crossing rate
We present the results of an R&D study for a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel and silicon strip detectors at , thus suitable for
processing LHC events at the full crossing frequency. For this purpose we
design and test a massively parallel pattern-recognition algorithm, inspired to
the current understanding of the mechanisms adopted by the primary visual
cortex of mammals in the early stages of visual-information processing. The
detailed geometry and charged-particle's activity of a large tracking detector
are simulated and used to assess the performance of the artificial retina
algorithm. We find that high-quality tracking in large detectors is possible
with sub-microsecond latencies when the algorithm is implemented in modern,
high-speed, high-bandwidth FPGA devices.Comment: 3 pages, 3 figures, ICHEP14. arXiv admin note: text overlap with
arXiv:1409.089
A Specialized Processor for Track Reconstruction at the LHC Crossing Rate
We present the results of an R&D study of a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel detectors at 40 MHz, thus suitable for processing LHC events at the full
crossing frequency. For this purpose we design and test a massively parallel
pattern-recognition algorithm, inspired by studies of the processing of visual
images by the brain as it happens in nature. We find that high-quality tracking
in large detectors is possible with sub-s latencies when this algorithm is
implemented in modern, high-speed, high-bandwidth FPGA devices. This opens a
possibility of making track reconstruction happen transparently as part of the
detector readout.Comment: Presented by G.Punzi at the conference on "Instrumentation for
Colliding Beam Physics" (INSTR14), 24 Feb to 1 Mar 2014, Novosibirsk, Russia.
Submitted to JINST proceeding
LHCb VELO Upgrade: Technical Design Report
The upgraded LHCb VELO silicon vertex detector is a lightweight hybrid pixel detector capable of 40 MHz readout at a luminosity of 2Ă10^33 cm^â2 s^â1. The track reconstruction speed and precision is enhanced relative to the current VELO detector even at the high occupancy conditions of the upgrade, due to the pixel geometry and a closest distance of approach to the LHC beams of just 5.1 mm for the first sensitive pixel. Cooling is provided by evaporative CO2 circulating in microchannel cooling substrates. The detector contains 41 million 55ÎŒĂ55ÎŒ pixels, read out by the custom developed VeloPix front end ASIC. The detector will start operation together with the rest of the upgraded LHCb experiment after the LHC LS2 shutdown, currently scheduled to end in 2019. This Technical Design Report describes the upgraded VELO system, planned construction and installation, and gives an overview of the expected detector performanc
Assessing conservation priorities of xenarthrans in Argentina
In this study, we combine species distribution models with a reserve selection approach to assess the degree of representation of xenarthrans in the existing protected area network of Argentina, and to identify conservation priority areas that may help expand the current system. Species distribution models were developed from speciesâ occurrence records using a maximum entropy algorithm. Maps of species distributions were produced for 15 of the 16 species currently present in the country. To assess the performance of the existing protected area network in representing all modeled species, and to identify priority areas to expand the current reserve system, we used the software Zonation. Overall, all species modeled are represented in the existing protected area network. However, the percentage of their ranges covered by protected areas is very low (average = 6.7%; range = 1.7â17.6%). To represent at least 5% of the distribution of each species, 8.8% of the countryâs area would be needed, and species with restricted ranges have the greatest increase in representation in this scenario. When 10% of the country is set aside for conservation, species representation increases considerably, again favoring range-restricted species. Most of the areas identified as conservation priorities are under strong anthropogenic pressures, including deforestation, agricultural expansion, and hunting. Our analysis provides a preliminary assessment of conservation priorities for the xenarthrans of Argentina, and we hope will serve as guideline to focus future conservation assessments at more refined scales.Facultad de Ciencias Naturales y Muse
Improving the Time Resolution of Large-Area LaBr3:Ce Detectors with SiPM Array Readout
LaBr3:Ce crystals have good scintillation properties for X-ray spectroscopy.
Initially, they were introduced for radiation imaging in medical physics with
either a photomultiplier or SiPM readout, and they found extensive applications
in homeland security and gamma-ray astronomy. We used 1 inch round LaBr3:Ce
crystals to realize compact detectors with the SiPM array readout. The aim was
a good energy resolution and a fast time response to detect low-energy X-rays
around 100 keV. A natural application was found inside the FAMU experiment, at
RIKEN RAL. Its aim is a precise measurement of the proton Zemach radius with
impinging muons, to contribute to the solution to the so-called proton radius
puzzle. Signals to be detected are characteristic X-rays around 130 KeV. A
limit for this type of detector, as compared to the ones with a photomultiplier
readout, is its poorer timing characteristics due to the large capacity of the
SiPM arrays used. In particular, long signal falltimes are a problem in
experiments such as FAMU, where a prompt background component must be separated
from a delayed one (after 600 ns) in the signal X-rays to be detected.
Dedicated studies were pursued to improve the timing characteristics of the
used detectors, starting from hybrid ganging of SiPM cells; then developing a
suitable zero pole circuit with a parallel ganging, where an increased
overvoltage for the SiPM array was used to compensate for the signal decrease;
and finally designing ad hoc electronics to split the 1 inch detector SiPM
array into four quadrants, thus reducing the involved capacitances. The aim was
to improve the detectors timing characteristics, especially falltime, while
keeping a good FWHM energy resolution for low-energy X-ray detection
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