510 research outputs found
Malaria
Malaria is a aisease of parasitical origin characterised
by splenic enlargement,brief febrile attacks
which recur periodically ,melanaemia,and a tendency in
protracted cases to irregular fever and extreme anaemia.
The most characteristic malarial manifestations
are intermittent or remittent fever, certain forms or
disease described as "pernicious", and a chronic cachexia
with enlargement of the spleen and anaemia
Analysis of Sardine Fisheries Management on Lake Kariba, Zimbabwe and Zambia - Structuring a Bayesian Influence Diagram Model
One of the main issues in the fisheries management of Lake Kariba is the question of how much the total effort of sardine fisheries can be increased without threatening the renewal of the stock and the economical profitability of the fisheries. This problem is subjected to uncertain natural processes and diverse and insufficient information available. A Bayesian influence diagram model was developed to analyze the decision problem. The Bayesian approach offers means for fusioning probabilistic information from different sources, and assessing the relative information value of quantities included in the model
MINE-NEC - A Game for the Analysis of Regional Water Policies in Open-Pit Lignite Mining Areas: An Improved Implementation for the NEC PC-8201A
The game MINE was developed for the analysis of regional water policies in open-pit lignite mining areas. It is implemented for a GDR test area. The purpose of the game is above all to teach decision makers and their staff in mining regions in order to get a better understanding of the complex interrelated socio-economic processes with respect t o water management in such regions. The game is designed to be played by five groups of players representing municipal and industrial water supply, agriculture, environmental protection and lignite mining.
In this paper an improved BASIC version for the portable NEC PC-8201A microcomputer is introduced
Comparison of novel fungal mycelia strains and sustainable growth substrates to produce humidity-resistant biocomposites
Fungal mycelia are versatile, highly productive and sustainable sources for biocomposites to replace conventional plastics. However, with only very few fungal strains that have been characterized, numerous strains still remain unexplored as potential competitors against traditional non-biodegradable materials. Moreover, the functionality of mycelium composites at commonly occurring, challenging ambient conditions such as changing humidity and temperature is not well characterized. Here we evaluated the properties of the fungal composite material produced by novel fungal strains, including Trichoderma asperellum and Agaricus bisporus, grown on oat husk and rapeseed cake after oil pressing. The results showed that the mycelium composites were hydrophobic and strong, particularly when grown on rapeseed cake. A. bisporus grown on rapeseed cake exhibited increased stiffness after humidity was successively increased and decreased. The moisture-resistance of these novel mycelium composites is encouraging for novel sustainable material solutions.Peer reviewe
The effect of microstructure on mechanical properties of HVOF sprayed WC-CoCr composite coatings
This study aims for deeper understanding of the composition and phase changes occurring during HVOF spraying of the powder to WC-CoCr coatings. Also, the effect of lamellar microstructure on the mechanical properties is studied. Compositional and microstructural features are studied by means of X-ray diffraction, XRF, FE-SEM and TEM (EDX, EELS). Mechanical properties are mainly studied by different instrumented indentation and nanoindentation techniques. The use of two new fracture parameters, complementing the fracture toughness value of the coating, are proposed and examined. Higher load range indentations are used to measure cross-sectional and surface hardness, elastic modulus and fracture toughness of the coatings. Mechanical properties of individual phases are studied by nanoindentation. To our knowledge this is the first time that the mechanical properties of this amorphous/nanocrystalline matrix are studied. ICP (In-situ Coating Property) sensor, developed for quality control and residual stress evaluation, is also used to measure the elastic modulus and coefficient of thermal expansion (CTE) of the coatings. Abrasion wear resistance of the coatings are studied according to standard ASTM G 65D.
Because of the brittle nature of HVOF coatings, the main focus of this study is in the effects of coating microstructure on fracture toughness, and on crack initiation and propagation resistance. It is shown that even when two similar coatings have equal indentation fracture toughness values, the critical crack initiation loads may be very different. This new parameter is expected to be extremely useful in the evaluation of the coating performance under loading conditions
Evaluating the impact of pyrethroid insecticide resistance on reproductive fitness in Sitobion avenae
Resistance to insecticides used to control pests is an issue of increasing concern for agriculture. The grain aphid, Sitobion avenae, is a pest of cereals and grasses worldwide, and one of growing concern due to the evolution of resistance to certain insecticides. Resistance confers benefits to insects by enabling them to survive exposure to insecticide compounds; however, the mutations conferring resistance may also penalise the insect in pesticide-free environments due to fitness costs associated with the new phenotype. Here we tested the hypothesis of a reproductive penalty linked to the knockdown resistance mutation (kdr) to pyrethroid insecticides. The mutation occurs predominantly in a single SA3 clone. To date, only heterozygous-resistant forms (kdr-SR) have been detected in populations in Ireland and the UK, and this suggests that a fitness penalty may preclude the formation of both male and female heterozygous-resistant sexual forms. By designing an experiment which included a resistant and a non-resistant clone, we were able to simulate reduced daylight and temperature conditions which, in nature, trigger sexual reproduction and therefore study the responses of each clone. This allowed us to detect the switch from asexual females to sexual females and males and report on the conditions associated with the production of sexual forms. The results showed that both aphid clones were able to produce sexual forms with no difference in the onset of sexual reproduction, although reproductive strategies differed between clones. The later onset of male forms in the SA3 clone may decrease the likelihood of mating interactions to create fully resistant (kdr-RR) genotypes and this may constitute a fitness penalty due to pyrethroid resistance
Planck-LFI radiometers' spectral response
The Low Frequency Instrument (LFI) is an array of pseudo-correlation
radiometers on board the Planck satellite, the ESA mission dedicated to
precision measurements of the Cosmic Microwave Background. The LFI covers three
bands centred at 30, 44 and 70 GHz, with a goal bandwidth of 20% of the central
frequency.
The characterization of the broadband frequency response of each radiometer
is necessary to understand and correct for systematic effects, particularly
those related to foreground residuals and polarization measurements. In this
paper we present the measured band shape of all the LFI channels and discuss
the methods adopted for their estimation. The spectral characterization of each
radiometer was obtained by combining the measured spectral response of
individual units through a dedicated RF model of the LFI receiver scheme.
As a consistency check, we also attempted end-to-end spectral measurements of
the integrated radiometer chain in a cryogenic chamber. However, due to
systematic effects in the measurement setup, only qualitative results were
obtained from these tests. The measured LFI bandpasses exhibit a moderate level
of ripple, compatible with the instrument scientific requirements.Comment: 16 pages, 9 figures, this paper is part of the Prelaunch status LFI
papers published on JINST:
http://www.iop.org/EJ/journal/-page=extra.proc5/jins
The linearity response of the Planck-LFI flight model receivers
In this paper we discuss the linearity response of the Planck-LFI receivers,
with particular reference to signal compression measured on the 30 and 44 GHz
channels. In the article we discuss the various sources of compression and
present a model that accurately describes data measured during tests performed
with individual radiomeric chains. After discussing test results we present the
best parameter set representing the receiver response and discuss the impact of
non linearity on in-flight calibration, which is shown to be negligible.Comment: this paper is part of the Prelaunch status LFI papers published on
JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jinst; This is an
author-created, un-copyedited version of an article accepted for publication
in JINST. IOP Publishing Ltd is not responsible for any errors or omissions
in this version of the manuscript or any version derived from it. The
definitive publisher authenticated version is available online at
10.1088/1748-0221/4/12/T12011
DNA copy number changes in young gastric cancer patients with special reference to chromosome 19
Only a few cytogenetic and genetic studies have been performed in gastric cancer patients in young age groups. In the present study we used the comparative genomic hybridisation (CGH) method to characterise frequent DNA copy number changes in 22 gastric cancer patients of 45 years or younger and three gastric cancer cell lines established from patients younger than 45 years. Analysis of DNA copy number changes revealed frequent DNA copy number increases at chromosomes 17q (52%), 19q (68%) and 20q (64%). To confirm the CGH results and to characterise the amplicon region on the most frequently amplified chromosome, chromosome 19, we carried out fluorescence in situ hybridisation (FISH) analysis and Southern blot analysis. Fluorescence in situ hybridisation with the bacterial artificial chromosome (BAC) clone mapped to 19q12 indicated a copy number increase in all eight tumour specimens studied. Southern blot analysis of six tumour specimens and three tumour cell lines, with five probes mapped to the 19q12-13.2 region, suggested cyclin E to be one of the candidate target genes in the 19q region for gastric cancer tumorigenesis. Cyclin E protein overexpression was verified in tumours with amplification on chromosome 19. Further studies are required to investigate the biological and clinical significance of 19q amplicon and cyclin E upregulation in gastric cancer of young patient
The Planck-LFI flight model composite waveguides
The Low Frequency Instrument on board the PLANCK satellite is designed to
give the most accurate map ever of the CMB anisotropy of the whole sky over a
broad frequency band spanning 27 to 77 GHz. It is made of an array of 22
pseudo-correlation radiometers, composed of 11 actively cooled (20 K) Front End
Modules (FEMs), and 11 Back End Modules (BEMs) at 300K. The connection between
the two parts is made with rectangular Wave Guides. Considerations of different
nature (thermal, electromagnetic and mechanical), imposed stringent
requirements on the WGs characteristics and drove their design. From the
thermal point of view, the WG should guarantee good insulation between the FEM
and the BEM sections to avoid overloading the cryocooler. On the other hand it
is essential that the signals do not undergo excessive attenuation through the
WG. Finally, given the different positions of the FEM modules behind the focal
surface and the mechanical constraints given by the surrounding structures,
different mechanical designs were necessary. A composite configuration of
Stainless Steel and Copper was selected to satisfy all the requirements. Given
the complex shape and the considerable length (about 1.5-2 m), manufacturing
and testing the WGs was a challenge. This work deals with the development of
the LFI WGs, including the choice of the final configuration and of the
fabrication process. It also describes the testing procedure adopted to fully
characterize these components from the electromagnetic point of view and the
space qualification process they underwent. Results obtained during the test
campaign are reported and compared with the stringent requirements. The
performance of the LFI WGs is in line with requirements, and the WGs were
successfully space qualified.Comment: this paper is part of the Prelaunch status LFI papers published on
JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/jins
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