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Sample records for loxodonta africana electronic

  1. Pulmonary aspergillosis in an African elephant (Loxodonta africana).

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    Kaim, Ute; Paltian, Vanja; Krudewig, Christiane; Nieder, Anne; Wohlsein, Peter

    2009-04-01

    A 26-year-old female African elephant (Loxodonta africana) with a history of purulent pododermatitis, recurrent abdominal pain, and severe weight loss died spontaneously after a period of deteriorating disease. The main pathological finding was a severe bilateral pyogranulomatous, partially necrotizing pneumonia with numerous intralesional fungal hyphae. At microbiological examination Aspergillus spp. were isolated. The present case indicates that mycotic pneumonia should to be considered as a differential diagnosis of pulmonary disorders in elephants.

  2. Being stressed outside the park — conservation of African elephants (Loxodonta africana) in Namibia

    OpenAIRE

    Hunninck, Louis; Ringstad, Iris; Jackson, Craig Ryan; May, Roelof Frans; Fossøy, Frode; Uiseb, Kenneth; Killian, Werner; Røskaft, Eivin

    2017-01-01

    The conservation of the African savanna elephant (Loxodonta africana) is of prime importance for many African countries. Interactions between elephants and humans are known to induce stress and thereby have the potential to affect elephants’ fitness. In Namibia, anthropogenic disturbances are increasing due to increasing human population size and development, particularly near protected areas, such as national parks. In this study, we investigated elephant stress levels in relation to their l...

  3. Conservation planning for a widespread, threatened species: WWF and the African elephant Loxodonta africana

    OpenAIRE

    Stephenson, Peter J.; Ntiamoa-Baidu, Yaa

    2017-01-01

    In a case study of conservation planning by a conservation organization working at a continental scale we examine how WWF identified and prioritized its African elephant Loxodonta africana conservation activities. We (1) review lessons learnt from previous work, (2) identify priority landscapes using biological criteria (e.g. population size and viability) and institutional criteria (e.g. feasibility, sustainability and cost-effectiveness of WWF interventions), and (3) conduct a threat analys...

  4. Strangulating intestinal obstructions in four captive elephants (Elephas maximus and Loxodonta africana).

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    Wiedner, Ellen B; Peddie, James; Peddie, Linda Reeve; Abou-Madi, Noha; Kollias, George V; Doyle, Charles; Lindsay, William A; Isaza, Ramiro; Terrell, Scott; Lynch, Tim M; Johnson, Kari; Johnson, Gary; Sammut, Charlie; Daft, Barbara; Uzal, Francisco

    2012-03-01

    Three captive-born (5-day-old, 8-day-old, and 4-yr-old) Asian elephants (Elephas maximus) and one captive-born 22-yr-old African elephant (Loxodonta africana) from three private elephant facilities and one zoo in the United States presented with depression, anorexia, and tachycardia as well as gastrointestinal signs of disease including abdominal distention, decreased borborygmi, tenesmus, hematochezia, or diarrhea. All elephants showed some evidence of discomfort including agitation, vocalization, or postural changes. One animal had abnormal rectal findings. Nonmotile bowel loops were seen on transabdominal ultrasound in another case. Duration of signs ranged from 6 to 36 hr. All elephants received analgesics and were given oral or rectal fluids. Other treatments included warm-water enemas or walking. One elephant underwent exploratory celiotomy. Three animals died, and the elephant taken to surgery was euthanized prior to anesthetic recovery. At necropsy, all animals had severe, strangulating intestinal lesions.

  5. Morphological aspects and composition of African elephant (Loxodonta africana ivory

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    E.J. Raubenheimer

    1999-07-01

    Full Text Available This study was aimed at determining the origin of the diamond shaped pattern and composition of ivory of the African elephant. Fragments of ivory and tusks were obtained through the National Parks Board from the Kruger Park, Addo Elephant Park, Kaokoveld, Caprivi, Etosha, Kavango and Tembe Elephant Park. Polished surfaces were prepared in different planes and examined with light and electron microscopical techniques. Analyses of the inorganic composition were performed using atomic absorption spectrophotometry, ion selective electrodes and inductively coupled optical emission spectroscopy. The total amino acid composition was determined with the aid of an amino acid analyser. Morphological investigations showed the distinctive diamond shaped pattern of ivory to be caused by the sinusoidal surface to pulpal course followed by odontoblastic tubules. This course is the result of pressure which builds up between tightly packed odontoblasts on their centripetal course along an ever decreasing pulpal circumference during formation of ivory. A total of 17 elements were detected in the inorganic fraction of ivory, some in concentrations as low as 0.25 ^g/g. The concentrations of calcium, magnesium, fluoride, cobalt and zinc showed statistically significant differences (P < 0.007 between selected regions and may prove valuable in distinguishing chemically between ivory from different geographical locations. The organic content of ivory showed 17 amino acids in varying concentrations. The possible causes of these variations are discussed.

  6. Being stressed outside the park—conservation of African elephants (Loxodonta africana) in Namibia

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    Ringstad, Iris H; Jackson, Craig R; May, Roel; Fossøy, Frode; Uiseb, Kenneth; Killian, Werner; Palme, Rupert; Røskaft, Eivin

    2017-01-01

    Abstract The conservation of the African savanna elephant (Loxodonta africana) is of prime importance for many African countries. Interactions between elephants and humans are known to induce stress and thereby have the potential to affect elephants’ fitness. In Namibia, anthropogenic disturbances are increasing due to increasing human population size and development, particularly near protected areas, such as national parks. In this study, we investigated elephant stress levels in relation to their land use, specifically their protection status, comparing elephants within Etosha National Park in Namibia with elephants residing outside the park. We noninvasively collected dung samples of 91 elephants and determined the concentration of faecal glucocorticoid metabolites (fGCM), an indicator of physiological stress. Elephants outside the park (N = 35) had significantly higher concentrations of fGCM than those inside ENP (N = 56), suggesting that, despite including community-based conservancies, unprotected areas are more stressful for elephants than protected areas, most likely due to increased interactions with humans. We also found that males had lower fGCM concentrations than females, but no significant effect of age, body size or group size was detected. Additionally, herd sizes were significantly smaller and calf recruitment was potentially lower in unprotected areas. These findings underpin the importance of protected areas such as ENP, while encouraging decision-makers to continue reducing and mitigating potential human-induced disturbances. PMID:29270294

  7. How Bees Deter Elephants: Beehive Trials with Forest Elephants (Loxodonta africana cyclotis in Gabon.

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    Steeve Ngama

    Full Text Available In Gabon, like elsewhere in Africa, crops are often sources of conflict between humans and wildlife. Wildlife damage to crops can drastically reduce income, amplifying poverty and creating a negative perception of wild animal conservation among rural people. In this context, crop-raiding animals like elephants quickly become "problem animals". To deter elephants from raiding crops beehives have been successfully employed in East Africa; however, this method has not yet been tested in Central Africa. We experimentally examined whether the presence of Apis mellifera adansonii, the African honey bee species present in Central Africa, deters forest elephants (Loxodonta Africana cyclotis from feeding on fruit trees. We show for the first time that the effectiveness of beehives as deterrents of elephants is related to bee activity. Empty hives and those housing colonies of low bee activity do not deter elephants all the time; but beehives with high bee activity do. Although elephant disturbance of hives does not impede honey production, there is a tradeoff between deterrence and the quantity of honey produced. To best achieve the dual goals of deterring elephants and producing honey colonies must maintain an optimum activity level of 40 to 60 bee movements per minute. Thus, beehives colonized by Apis mellifera adansonii bees can be effective elephant deterrents, but people must actively manage hives to maintain bee colonies at the optimum activity level.

  8. Acute death associated with Citrobacter freundii infection in an African elephant (Loxodonta africana).

    Science.gov (United States)

    Ortega, Joaquín; Corpa, Juan M; Orden, José A; Blanco, Jorge; Carbonell, María D; Gerique, Amalia C; Latimer, Erin; Hayward, Gary S; Roemmelt, Andreas; Kraemer, Thomas; Romey, Aurore; Kassimi, Labib B; Casares, Miguel

    2015-09-01

    A 21-year-old male African elephant (Loxodonta africana) died suddenly with no previous medical history. Grossly, there were severe multifocal epicardial and endocardial hemorrhages of the atria and ventricles, hydropericardium, multifocal pleural hemorrhages, and severe pulmonary congestion and edema. Histologically, there was fibrinoid vasculitis and thrombosis in the heart and lung and myocardial necrosis. Citrobacter freundii was isolated in abundance in pure culture from liver and heart samples. Low levels of multiples types of elephant endotheliotropic herpesvirus (EEHV-6, EEHV-2B, and EEHV-3A) were detected in spleen samples, but not in heart samples. The levels of EEHV DNA found were much lower than those usually associated with acute EEHV hemorrhagic disease, and many other genomic loci that would normally be found in such cases were evidently below the level of detection. Therefore, these findings are unlikely to indicate lethal EEHV disease. Polymerase chain reaction for encephalomyocarditis virus (EMCV) and toxicology for oleander (Nerium oleander) were negative. Stress, resulting from recent transport, and antimicrobial therapy may have contributed to the death of this animal. © 2015 The Author(s).

  9. Etorphine-halothane anaesthesia in two five-year-old African elephants (Loxodonta africana : clinical communication

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    G.F. Stegmann

    1999-07-01

    Full Text Available Anaesthesia of 2 five-year-old femaleAfrican elephants (Loxodonta africana was required for dental surgery. The animals were each premedicated with 120 mg of azaperone 60 min before transportation to the hospital. Before offloading, 1 mg etorphine was administered intramuscularly (i.m. to each elephant to facilitate walking them to the equine induction / recovery room. For induction, 2 mg etorphine was administered i.m. to each animal. Induction was complete within 6 min. Surgical anaesthesia was induced with halothane-in-oxygen after intubation of the trunk. During surgery the mean heart rate was 61 and 45 beats / min respectively. Systolic blood pressures increased to 27.5 and 25.6 kPa respectively, and were treated with intravenous azaperone. Blood pressure decreased thereafter to a mean systolic pressure of 18.1 and 19.8 kPa, respectively. Rectal temperature was 35.6 and 33.9 oC at the onset of surgery, and decreased to 35.3 and 33.5 oC, respectively, at the end of anaesthesia. Etorphine anaesthesia was reversed with 5mg diprenorphine at the completion of 90 min of surgery.

  10. Molecular characterization of adipose tissue in the African elephant (Loxodonta africana.

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    Emeli M Nilsson

    Full Text Available Adipose tissue (AT is a dynamic and flexible organ with regulatory roles in physiological functions including metabolism, reproduction and inflammation; secreted adipokines, including leptin, and fatty acids facilitate many of these roles. The African elephant (Loxodonta africana is experiencing serious challenges to optimal reproduction in captivity. The physiological and molecular basis of this impaired fertility remains unknown. AT production of leptin is a crucial molecular link between nutritional status, adiposity and fertility in many species. We propose that leptin has a similar function in the African elephant. African elephant visceral and subcutaneous adipose tissue (AT was obtained from both sexes and a range of ages including females with known pregnancy status. RNA was extracted and histological sections created and analyzed by microarray, PCR and immunohistochemistry respectively. Gas-chromatography was used to determine the fatty acid composition of AT. Microarray expression profiling was used to compare gene expression profiles of AT from pre-pubertal versus reproductively competent adult African elephants. This study demonstrates, for the first time, leptin mRNA and protein expression in African elephant AT. The derived protein sequence of the elephant leptin protein was exploited to determine its relationship within the class I helical cytokine superfamily, which indicates that elephant leptin is most closely related to the leptin orthologs of Oryctolagus cuniculus (European rabbit, Lepus oiostolus (woolly hare, and members of the Ochotonidae (Pika. Immunohistological analysis identified considerable leptin staining within the cytoplasm of adipocytes. Significant differences in fatty acid profiles between pregnant and non-pregnant animals were revealed, most notably a reduction in both linoleic and α linoleic acid in pregnant animals. This report forms the basis for future studies to address the effect of nutrient composition

  11. Renaut bodies in nerves of the trunk of the African elephant, Loxodonta africana.

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    Witter, Kirsti; Egger, Gunter F; Boeck, Peter

    2007-05-01

    Renaut bodies are loosely textured, cell-sparse structures in the subperineurial space of peripheral nerves, frequently found at sites of nerve entrapment. The trunk of the elephant is a mobile, richly innervated organ, which serves for food gathering, object grasping and as a tactile organ. These functions of the trunk lead to distortion and mechanical compression of its nerves, which can therefore be expected to contain numerous Renaut bodies. Samples of the trunk wall of an adult African elephant (Loxodonta africana) were examined histologically using conventional staining methods, immunohistochemistry, and lectin histochemistry. Architecture of nerve plexuses and occurrence of Renaut bodies in the elephant trunk were compared with those in tissues surrounding the nasal vestibule of the pig. Prominent nerve plexuses were found in all layers of the elephant trunk. Almost all (81%) nerve profiles contained Renaut bodies, a basophilic, discrete subperineurial layer resembling cushions around the nerve core. In contrast, Renaut bodies were seen in only 15% of nerve profiles in the porcine nasal vestibule. Within Renaut bodies, fusiform fibroblasts and round, ruff-like cells were placed into a matrix of acidic glycosaminoglycans with delicate collagen and very few reticular fibers. The turgor of this matrix is thought to protect nerves against compression and shearing strain. Renaut bodies are readily stained with alcian blue (pH 2.5) favorably in combination with immunohistochemical markers of nerve fibers. They should be regarded as a physiological response to repeated mechanical insults and are distinct from pathological alterations. alterations. (c) 2007 Wiley-Liss, Inc.

  12. Standing sedation in African elephants (Loxodonta africana) using detomidine-butorphanol combinations.

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    Neiffer, Donald L; Miller, Michele A; Weber, Martha; Stetter, Mark; Fontenot, Deidre K; Robbins, P K; Pye, Geoffrey W

    2005-06-01

    Standing sedation was provided for 14 clinical procedures in three African elephants (Loxodonta africana) managed by combined protected and modified-protected contact and trained through operant conditioning. An initial hand-injection of detomidine hydrochloride and butorphanol tartrate at a ratio of 1:1 on a microg:microg basis was administered intramuscularly, with a dosage range of 50-70 mg (12.9-19.7 microg/kg) for each drug. The initial injection resulted in adequate sedation for initiation and completion of eight procedures, whereas supplemental doses were required for the remaining procedures. The dosage range for the supplemental injections of each drug was 4.0-7.3 microg/kg. Initial effect was noted within 3.0-25 min (mean = 11.6 min, SD +/- 5.9 min), with maximal effect occurring at 25-30 min for those procedures not requiring supplementation. In all but one procedure, this effect was maintained until the end of the procedure, which ranged from 47 to 98 min (mean = 74.7 min, SD +/- 18.8 min). No cardiac or respiratory depression was appreciated. Recovery after administration of reversal agents was rapid and complete, ranging from 2 to 20 min (mean = 9.0 min, SD +/- 7.0 min). On the basis of the authors' experience, recommended dosage ranges for reversal agents would be intravenous yohimbine (73.4-98.5 microg/kg), intravenous naltrexone (48.9-98.5 microg/kg), and intramuscular naltrexone (73.4-98.5 microg/kg). Approximately one-third to one-half of the total naltrexone dose should be administered intravenously. Mild adverse side effects limited to the gastrointestinal tract were observed in association with five procedures including abdominal distention with or without transient anorexia. Administration of reversal agents, encouraging exercise and water consumption, and administration of flunixin meglumine were helpful in the resolution of signs. In addition to gastrointestinal signs, slight ataxia was observed before initiation of surgical stimulation

  13. SUCCESSFUL TREATMENT OF DIGITAL OSTEITIS BY INTRAVENOUS REGIONAL PERFUSION OF CEFTIOFUR IN AN AFRICAN ELEPHANT (LOXODONTA AFRICANA).

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    Dutton, Christopher J; Delnatte, Pauline G; Hollamby, Simon R; Crawshaw, Graham J

    2017-06-01

    A 41-yr-old African elephant ( Loxodonta africana ) presented with a swollen third digit of the left forelimb and a 2-cm hole in the pad. Corrective trimming, topical treatments, and an oral antibiotic resulted in apparent resolution; however, it reoccurred after 4 mo. Radiographs suggested bone lysis in the third phalanx, with the primary differential diagnosis being septic osteitis. Flushing with metronidazole solution and intravenous regional perfusion (IVRP) of the foot were commenced. A tourniquet was applied just above the carpus, an interdigital vein was identified by ultrasound, and into this vein 2 g (20 ml) of ceftiofur sodium solution, followed by 60 ml of heparinized saline, was administered. The foot was kept raised for 25 min and then the tourniquet was removed. IVRP was repeated every other day for 70 treatments over 6 mo. Healing occurred, which was confirmed radiographically. IVRP offers an excellent treatment modality in a well-trained elephant.

  14. Enduring consequences of early experiences: 40 year effects on survival and success among African elephants (Loxodonta africana).

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    Lee, Phyllis C; Bussière, Luc F; Webber, C Elizabeth; Poole, Joyce H; Moss, Cynthia J

    2013-04-23

    Growth from conception to reproductive onset in African elephants (Loxodonta africana) provides insights into phenotypic plasticity, individual adaptive plastic responses and facultative maternal investment. Using growth for 867 and life histories for 2652 elephants over 40 years, we demonstrate that maternal inexperience plus drought in early life result in reduced growth rates for sons and higher mortality for both sexes. Slow growth during early lactation was associated with smaller adult size, later age at first reproduction, reduced lifetime survival and consequently limited reproductive output. These enduring effects of trading slow early growth against immediate survival were apparent over the very long term; delayed downstream consequences were unexpected for a species with a maximum longevity of 70+ years and unpredictable environmental experiences.

  15. Assessment of Flooring Renovations on African Elephant (Loxodonta africana) Behavior and Glucocorticoid Response

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    Boyle, Sarah A.; Roberts, Beth; Pope, Brittany M.; Blake, Margaret R.; Leavelle, Stephen E.; Marshall, Jennifer J.; Smith, Andrew; Hadicke, Amanda; Falcone, Josephine F.; Knott, Katrina; Kouba, Andrew J.

    2015-01-01

    Captive African (Loxodonta africana) and Asian (Elephas maximus) elephants can experience foot pathologies and arthritis. As a preventative measure against these pathologies and to alleviate the potential discomfort due to concrete substrates, some zoological institutions have renovated elephant housing to increase the amount of natural or shock-absorbent substrates. The objective of this study was to compare behavioral (diurnal and nocturnal) and glucorticoid (e.g., serum cortisol) responses of three female African elephants before, during, and after renovation to their indoor housing floor to assess whether renovations had short-term effects on the elephants’ behavior and stress physiology. Behavioral data were collected using scan-sampling methods, and activity budgets were constructed for each of the three elephants. In addition, the duration of all lying rest activities were recorded. Weekly serum cortisol concentrations were determined with enzyme immunoassay (EIA). Overall, eating was the most prevalent behavior exhibited outdoors during the day, while resting (either in a lying or standing position) were most common during the indoor, nocturnal periods. Although variation existed among the three elephants, all three females spent significantly more time walking and less time eating during the day after the completion of the renovations. The extent to which the three elephants exhibited nocturnal lying rest behavior varied among the elephants, with the oldest elephant exhibiting the least amount (an average of 13.2 ± 2.8% of the nightly behavioral scans) compared to the two younger elephants (an average of 34.5 ± 2.1% and 56.6 ± 2.8% of the nightly behavioral scans). There was a significant increase in lying rest behavior for one elephant and standing rest for a second elephant following renovations. Baseline cortisol concentrations prior to renovations were 3.0 ± 0.4 ng/ml, 4.5 ± 0.5 ng/ml, and 4.9 ± 0.5 ng/ml for the three elephants. Cortisol

  16. Assessment of Flooring Renovations on African Elephant (Loxodonta africana Behavior and Glucocorticoid Response.

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    Sarah A Boyle

    Full Text Available Captive African (Loxodonta africana and Asian (Elephas maximus elephants can experience foot pathologies and arthritis. As a preventative measure against these pathologies and to alleviate the potential discomfort due to concrete substrates, some zoological institutions have renovated elephant housing to increase the amount of natural or shock-absorbent substrates. The objective of this study was to compare behavioral (diurnal and nocturnal and glucorticoid (e.g., serum cortisol responses of three female African elephants before, during, and after renovation to their indoor housing floor to assess whether renovations had short-term effects on the elephants' behavior and stress physiology. Behavioral data were collected using scan-sampling methods, and activity budgets were constructed for each of the three elephants. In addition, the duration of all lying rest activities were recorded. Weekly serum cortisol concentrations were determined with enzyme immunoassay (EIA. Overall, eating was the most prevalent behavior exhibited outdoors during the day, while resting (either in a lying or standing position were most common during the indoor, nocturnal periods. Although variation existed among the three elephants, all three females spent significantly more time walking and less time eating during the day after the completion of the renovations. The extent to which the three elephants exhibited nocturnal lying rest behavior varied among the elephants, with the oldest elephant exhibiting the least amount (an average of 13.2 ± 2.8% of the nightly behavioral scans compared to the two younger elephants (an average of 34.5 ± 2.1% and 56.6 ± 2.8% of the nightly behavioral scans. There was a significant increase in lying rest behavior for one elephant and standing rest for a second elephant following renovations. Baseline cortisol concentrations prior to renovations were 3.0 ± 0.4 ng/ml, 4.5 ± 0.5 ng/ml, and 4.9 ± 0.5 ng/ml for the three elephants

  17. The impact of male contraception on dominance hierarchy and herd association patterns of African elephants (Loxodonta africana) in a fenced game reserve

    OpenAIRE

    L.S. Doughty; K. Slater; H. Zitzer; Tomos Avent; S. Thompson

    2014-01-01

    Overpopulation of African elephants (Loxodonta africana) in fenced reserves in South Africa is becoming increasingly problematic to wildlife managers. With growing opposition to culling and the high cost of translocation, alternative management strategies focusing on male elephants are being investigated. In this study, hormonal treatment via Gonadotropin Releasing Hormone (GnRH) suppression, and surgical treatment via vasectomy were trialled. Focusing on behavioural responses, we tested the ...

  18. Determinants of seasonal changes in availability of food patches for elephants (Loxodonta africana in a semi-arid African savanna

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    Bruce W. Clegg

    2017-06-01

    Full Text Available Loss of biodiversity caused by impact of elephants (Loxodonta africana on African woodlands may require a management response, but any action should be based on an understanding of why elephants choose to utilise trees destructively. Comprehension of elephant feeding behaviour requires consideration of the relative value of the plant groups they may potentially consume. Profitability of available food is partly determined by the time to locate a food patch and, therefore, as a foundation for understanding the influence of food availability on diet selection, key controls on the density of grass, forb, and browse patches were investigated across space and time in a semi-arid African savanna. Density of food patches changed seasonally because plant life-forms required different volumes of soil water to produce green forage; and woody plants and forbs responded to long-term changes in soil moisture, while grasses responded to short-term moisture pulses. Soil texture, structure of woody vegetation and fire added further complexity by altering the soil water thresholds required for production of green forage. Interpolating between regularly-timed, ground-based measurements of food density by using modelled soil water as the predictor in regression equations may be a feasible method of quantifying food available to elephants in complex savanna environments.

  19. Elephant (Loxodonta africana home ranges in Sabi Sand Reserve and Kruger National Park: a five-year satellite tracking study.

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    Bindi Thomas

    Full Text Available During a five-year GPS satellite tracking study in Sabi Sand Reserve (SSR and Kruger National Park (KNP we monitored the daily movements of an elephant cow (Loxodonta africana from September 2003 to August 2008. The study animal was confirmed to be part of a group of seven elephants therefore her position is representative of the matriarchal group. We found that the study animal did not use habitat randomly and confirmed strong seasonal fidelity to its summer and winter five-year home ranges. The cow's summer home range was in KNP in an area more than four times that of her SSR winter home range. She exhibited clear park habitation with up to three visits per year travelling via a well-defined northern or southern corridor. There was a positive correlation between the daily distance the elephant walked and minimum daily temperature and the elephant was significantly closer to rivers and artificial waterholes than would be expected if it were moving randomly in KNP and SSR. Transect lines established through the home ranges were surveyed to further understand the fine scale of the landscape and vegetation representative of the home ranges.

  20. Elephant (Loxodonta africana) home ranges in Sabi Sand Reserve and Kruger National Park: a five-year satellite tracking study.

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    Thomas, Bindi; Holland, John D; Minot, Edward O

    2008-01-01

    During a five-year GPS satellite tracking study in Sabi Sand Reserve (SSR) and Kruger National Park (KNP) we monitored the daily movements of an elephant cow (Loxodonta africana) from September 2003 to August 2008. The study animal was confirmed to be part of a group of seven elephants therefore her position is representative of the matriarchal group. We found that the study animal did not use habitat randomly and confirmed strong seasonal fidelity to its summer and winter five-year home ranges. The cow's summer home range was in KNP in an area more than four times that of her SSR winter home range. She exhibited clear park habitation with up to three visits per year travelling via a well-defined northern or southern corridor. There was a positive correlation between the daily distance the elephant walked and minimum daily temperature and the elephant was significantly closer to rivers and artificial waterholes than would be expected if it were moving randomly in KNP and SSR. Transect lines established through the home ranges were surveyed to further understand the fine scale of the landscape and vegetation representative of the home ranges.

  1. Housing and Social Environments of African (Loxodonta africana) and Asian (Elephas maximus) Elephants in North American Zoos.

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    Meehan, Cheryl L; Hogan, Jennifer N; Bonaparte-Saller, Mary K; Mench, Joy A

    2016-01-01

    We evaluated 255 African (Loxodonta africana) and Asian (Elephas maximus) elephants living in 68 North American zoos over one year to quantify housing and social variables. All parameters were quantified for the both the day and the night and comparisons were made across these time periods as well as by species and sex. To assess housing, we evaluated not only total exhibit size, but also individual animals' experiences based on the time they spent in the unique environments into which the exhibits were subdivided. Variables developed to assess housing included measurements of area as a function of time (Total Space Experience), environment type (Indoor, Outdoor, In/Out Choice) and time spent on hard and soft flooring. Over the year, Total Space Experience values ranged from 1,273 square feet to 169,692 square feet, with Day values significantly greater than Night values (pElephants spent an average of 55.1% of their time outdoors, 28.9% indoors, and 16% in areas with a choice between being in or out. Time spent on hard flooring substrate ranged from 0% to 66.7%, with Night values significantly greater than Day (pelephants having larger Total Space Experience than Asian and female elephants, respectively (P-valueelephant welfare outcomes.

  2. Slon africký (Loxodonta africana, Blumenbach 1797),rešerše literatury se zaměřením na paměť a učení

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    Křivánek, Ondřej

    2012-01-01

    This BA thesis is a data retrieval aimed at the African elephant (Loxodonta africana). The present paper deals with the evolution, the specific anatomy and physiology, nutrition, communication, migration, daily routine, social behavior and reproduction of the African elephant. The main body of this study is, howewer, a report on the research on its memory and learning. The text has been compiled using scientific research papers and textbooks. Key words: African elephant, Loxodonta, anatomy, p...

  3. The social and ecological integration of captive-raised adolescent male African elephants (Loxodonta africana into a wild population.

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    Kate Evans

    Full Text Available BACKGROUND: A rapid rise in the number of captive African elephants (Loxodonta africana used in the tourism industry in southern Africa and orphaned elephants in human care has led to concerns about their long-term management, particularly males. One solution is to release them into the wild at adolescence, when young males naturally leave their herd. However, this raises significant welfare concerns: little is known about how well released elephants integrate into wild populations and whether they pose a greater threat to humans than wild elephants. We document the release of three captive-raised adolescent male African elephants in the Okavango Delta, Botswana. METHODOLOGY/PRINCIPAL FINDINGS: Despite having been part of a herd of working elephants for at least eight years, the three males progressively integrated into the complex fission-fusion society of wild bull elephants. In the three years following release, they showed no tendency to be closer to human habitation, and there were no significant differences between wild and captive-raised adolescent males in the total number of social interactions, size of ranges and habitat use. However, the captive-raised elephants sparred less and vocalised more, and spent more time alone and in smaller social groups. Thereafter the released elephants continued to expand their ranges and interact with both mixed-sex herds and males. One male was shot by farmers 94 months after release, along with ten wild elephants, on a ranch outside the protected area. CONCLUSIONS/SIGNIFICANCE: We show that captive-raised adolescent male elephants can integrate into a wild population. Long-term studies are required to determine the longevity, breeding success, and eventual fate of released male elephants, but we identified no significant short-term welfare problems for the released elephants or recipient population. Release of captive-raised mammals with complex social systems is a husbandry option that should be

  4. Housing and Social Environments of African (Loxodonta africana and Asian (Elephas maximus Elephants in North American Zoos.

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    Cheryl L Meehan

    Full Text Available We evaluated 255 African (Loxodonta africana and Asian (Elephas maximus elephants living in 68 North American zoos over one year to quantify housing and social variables. All parameters were quantified for the both the day and the night and comparisons were made across these time periods as well as by species and sex. To assess housing, we evaluated not only total exhibit size, but also individual animals' experiences based on the time they spent in the unique environments into which the exhibits were subdivided. Variables developed to assess housing included measurements of area as a function of time (Total Space Experience, environment type (Indoor, Outdoor, In/Out Choice and time spent on hard and soft flooring. Over the year, Total Space Experience values ranged from 1,273 square feet to 169,692 square feet, with Day values significantly greater than Night values (p<0.001. Elephants spent an average of 55.1% of their time outdoors, 28.9% indoors, and 16% in areas with a choice between being in or out. Time spent on hard flooring substrate ranged from 0% to 66.7%, with Night values significantly greater than Day (p<0.001. Social factors included number of animals functionally housed together (Social Experience and social group characteristics such as time spent with juveniles and in mixed-sex groups. Overall Social Experience scores ranged from 1 to 11.2 and were significantly greater during the Day than at Night (p<0.001. There were few significant social or housing differences between African (N = 138 and Asian (N = 117 species or between males (N = 54 and females (N = 201. The most notable exception was Total Space Experience, with African and male elephants having larger Total Space Experience than Asian and female elephants, respectively (P-value<0.05. The housing and social variables evaluated herein have been used in a series of subsequent epidemiological analyses relating to various elephant welfare outcomes.

  5. First report of changes in leukocyte morphology in response to inflammatory conditions in Asian and African elephants (Elephas maximus and Loxodonta africana.

    Directory of Open Access Journals (Sweden)

    Nicole I Stacy

    Full Text Available Although the hematology of healthy elephants has been well-described, published information on hematological changes during disease is limited. The objective of this study was to describe qualitative morphological changes in the leukocytes of Asian and African elephants (Elephas maximus and Loxodonta africana diagnosed with a variety of inflammatory conditions. Twenty-five of 27 elephants had morphological changes in their leukocytes, although only 16 of these had a concurrent inflammatory leukogram. Morphological changes included heterophil left-shifting with or without concurrent dysgranulopoiesis, toxicity, or hypersegmentation, reactive lymphocytes, plasma cells, and/or vacuolated monocytes. Although the observed leukocyte morphological changes are non-specific, their early recognition upon blood film evaluation may provide important, clinically-relevant information, particularly if the leukogram is normal. This case series is the first description of qualitative morphological changes in the leukocytes of elephants in association with inflammation.

  6. USE OF COMPOSITE MATERIALS AS A COMPONENT OF TUSK FRACTURE MANAGEMENT IN AN ASIAN ELEPHANT (ELEPHAS MAXIMUS) AND AN AFRICAN ELEPHANT (LOXODONTA AFRICANA).

    Science.gov (United States)

    Sim, Richard R; Stringer, Elizabeth; Donovan, Dennis; Chappell, Rachael; Flora, Pat; Hall, Jon; Pillay, Selvum; Willis, Benjamin G; McCain, Stephanie

    2017-09-01

    Tusk fractures in Asian (Elephas maximus) and African elephants (Loxodonta africana) can result in damage to the distal end or to longitudinal cracks, potentially progressing to pulpitis. With pulp exposure, endodontic therapy is the treatment of choice, but conservative therapy has sufficed for some elephants. This manuscript describes the use of composite materials as a component of tusk fracture management. A 7-yr-old male Asian elephant fractured the distal end of both tusks with pulp exposure in one. Capping of each tusk with a Kevlar/fiberglass composite prevented further damage, and a modification allowed care of the exposed pulp tissue. A 34-yr-old male African elephant with a longitudinal crack received a carbon fiber/fiberglass composite circumferential wrap to potentially stabilize the crack. Compression of the crack was achieved, but follow-up was truncated due to bacterial pulpitis. Both cases show that composite material allows for lightweight, durable management of tusk fractures with continued radiographic monitoring.

  7. Loxodonta africana (Blumenbach)

    African Journals Online (AJOL)

    lose-content of the diet of ruminants and non-ruminants. The elephant, like the equidae, exists on a diet with a high cellulose content, and the length of the intestinal canal from the stomach to the ..... Studies on the evolution of the ophryoscolecidae. (Ciliata:Oligotricha) III. Phylogeny of the Ophryoscolecidae based on.

  8. Assessment of Body Condition in African (Loxodonta africana and Asian (Elephas maximus Elephants in North American Zoos and Management Practices Associated with High Body Condition Scores.

    Directory of Open Access Journals (Sweden)

    Kari A Morfeld

    Full Text Available Obesity has a negative effect on health and welfare of many species, and has been speculated to be a problem for zoo elephants. To address this concern, we assessed the body condition of 240 elephants housed in North American zoos based on a set of standardized photographs using a 5-point Body Condition Score index (1 = thinnest; 5 = fattest. A multi-variable regression analysis was then used to determine how demographic, management, housing, and social factors were associated with an elevated body condition score in 132 African (Loxodonta africana and 108 Asian (Elephas maximus elephants. The highest BCS of 5, suggestive of obesity, was observed in 34% of zoo elephants. In both species, the majority of elephants had elevated BCS, with 74% in the BCS 4 (40% and 5 (34% categories. Only 22% of elephants had BCS 3, and less than 5% of the population was assigned the lowest BCS categories (BCS 1 and 2. The strongest multi-variable model demonstrated that staff-directed walking exercise of 14 hours or more per week and highly unpredictable feeding schedules were associated with decreased risk of BCS 4 or 5, while increased diversity in feeding methods and being female was associated with increased risk of BCS 4 or 5. Our data suggest that high body condition is prevalent among North American zoo elephants, and management strategies that help prevent and mitigate obesity may lead to improvements in welfare of zoo elephants.

  9. Housing and Demographic Risk Factors Impacting Foot and Musculoskeletal Health in African Elephants [Loxodonta africana] and Asian Elephants [Elephas maximus] in North American Zoos.

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    Michele A Miller

    Full Text Available For more than three decades, foot and musculoskeletal conditions have been documented among both Asian [Elephas maximus] and African [Loxodonta africana] elephants in zoos. Although environmental factors have been hypothesized to play a contributing role in the development of foot and musculoskeletal pathology, there is a paucity of evidence-based research assessing risk. We investigated the associations between foot and musculoskeletal health conditions with demographic characteristics, space, flooring, exercise, enrichment, and body condition for elephants housed in North American zoos during 2012. Clinical examinations and medical records were used to assess health indicators and provide scores to quantitate conditions. Using multivariable regression models, associations were found between foot health and age [P value = 0.076; Odds Ratio = 1.018], time spent on hard substrates [P value = 0.022; Odds Ratio = 1.014], space experienced during the night [P value = 0.041; Odds Ratio = 1.008], and percent of time spent in indoor/outdoor exhibits during the day [P value < 0.001; Odds Ratio = 1.003]. Similarly, the main risk factors for musculoskeletal disorders included time on hard substrate [P value = 0.002; Odds Ratio = 1.050] and space experienced in indoor/outdoor exhibits [P value = 0.039; Odds Ratio = 1.037]. These results suggest that facility and management changes that decrease time spent on hard substrates will improve elephant welfare through better foot and musculoskeletal health.

  10. The impact of male contraception on dominance hierarchy and herd association patterns of African elephants (Loxodonta africana in a fenced game reserve

    Directory of Open Access Journals (Sweden)

    L.S. Doughty

    2014-12-01

    Full Text Available Overpopulation of African elephants (Loxodonta africana in fenced reserves in South Africa is becoming increasingly problematic to wildlife managers. With growing opposition to culling and the high cost of translocation, alternative management strategies focusing on male elephants are being investigated. In this study, hormonal treatment via Gonadotropin Releasing Hormone (GnRH suppression, and surgical treatment via vasectomy were trialled. Focusing on behavioural responses, we tested the male dominance hierarchy for transitivity, and examined the rank order of individuals in relation to age and contraceptive treatment received. Additionally, we studied association patterns between males within the male population and with the female herds.Findings suggest that the treatment of one individual with GnRH suppressant is affecting the rank order of the dominance hierarchy, though it is still transitive, yet fluid (Landau’s linearity index h=0.7, as expected in a normal elephant population. Between males, association patterns were found to be weak. However, some males had relatively strong associations with the female herds, with association indices between 0.25 and 0.41. This suggests that the reduction on births is resulting in the males spending atypically large amounts of time with the female herds. The future conservation implications of this population control mechanism are discussed. Keywords: African elephant, Population control, Contraception, Social dynamics, Dominance, Association patterns

  11. The mummified brain of a pleistocene woolly mammoth (Mammuthus primigenius) compared with the brain of the extant African elephant (Loxodonta africana).

    Science.gov (United States)

    Kharlamova, Anastasia S; Saveliev, Sergei V; Protopopov, Albert V; Maseko, Busisiwe C; Bhagwandin, Adhil; Manger, Paul R

    2015-11-01

    This study presents the results of an examination of the mummified brain of a pleistocene woolly mammoth (Mammuthus primigenius) recovered from the Yakutian permafrost in Siberia, Russia. This unique specimen (from 39,440-38,850 years BP) provides the rare opportunity to compare the brain morphology of this extinct species with a related extant species, the African elephant (Loxodonta africana). An anatomical description of the preserved brain of the woolly mammoth is provided, along with a series of quantitative analyses of various brain structures. These descriptions are based on visual inspection of the actual specimen as well as qualitative and quantitative comparison of computed tomography imaging data obtained for the woolly mammoth in comparison with magnetic resonance imaging data from three African elephant brains. In general, the brain of the woolly mammoth specimen examined, estimated to weigh between 4,230 and 4,340 g, showed the typical shape, size, and gross structures observed in extant elephants. Quantitative comparative analyses of various features of the brain, such as the amygdala, corpus callosum, cerebellum, and gyrnecephalic index, all indicate that the brain of the woolly mammoth specimen examined has many similarities with that of modern African elephants. The analysis provided here indicates that a specific brain type representative of the Elephantidae is likely to be a feature of this mammalian family. In addition, the extensive similarities between the woolly mammoth brain and the African elephant brain indicate that the specializations observed in the extant elephant brain are likely to have been present in the woolly mammoth. © 2015 Wiley Periodicals, Inc.

  12. The Days and Nights of Zoo Elephants: Using Epidemiology to Better Understand Stereotypic Behavior of African Elephants (Loxodonta africana and Asian Elephants (Elephas maximus in North American Zoos.

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    Brian J Greco

    Full Text Available Stereotypic behavior is an important indicator of compromised welfare. Zoo elephants are documented to perform stereotypic behavior, but the factors that contribute to performance have not been systematically assessed. We collected behavioral data on 89 elephants (47 African [Loxodonta africana], 42 Asian [Elephas maximus] at 39 North American zoos during the summer and winter. Elephants were videoed for a median of 12 daytime hours per season. A subset of 32 elephants (19 African, 13 Asian was also observed live for a median of 10.5 nighttime hours. Percentages of visible behavior scans were calculated from five minute instantaneous samples. Stereotypic behavior was the second most commonly performed behavior (after feeding, making up 15.5% of observations during the daytime and 24.8% at nighttime. Negative binomial regression models fitted with generalized estimating equations were used to determine which social, housing, management, life history, and demographic variables were associated with daytime and nighttime stereotypic behavior rates. Species was a significant risk factor in both models, with Asian elephants at greater risk (daytime: p<0.001, Risk Ratio = 4.087; nighttime: p<0.001, Risk Ratio = 8.015. For both species, spending time housed separately (p<0.001, Risk Ratio = 1.009, and having experienced inter-zoo transfers (p<0.001, Risk Ratio = 1.175, increased the risk of performing higher rates of stereotypy during the day, while spending more time with juvenile elephants (p<0.001, Risk Ratio = 0.985, and engaging with zoo staff reduced this risk (p = 0.018, Risk Ratio = 0.988. At night, spending more time in environments with both indoor and outdoor areas (p = 0.013, Risk Ratio = 0.987 and in larger social groups (p = 0.039, Risk Ratio = 0.752 corresponded with reduced risk of performing higher rates of stereotypy, while having experienced inter-zoo transfers (p = 0.033, Risk Ratio = 1.115 increased this risk. Overall, our results

  13. Reproductive Health Assessment of Female Elephants in North American Zoos and Association of Husbandry Practices with Reproductive Dysfunction in African Elephants (Loxodonta africana.

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    Janine L Brown

    Full Text Available As part of a multi-institutional study of zoo elephant welfare, we evaluated female elephants managed by zoos accredited by the Association of Zoos and Aquariums and applied epidemiological methods to determine what factors in the zoo environment are associated with reproductive problems, including ovarian acyclicity and hyperprolactinemia. Bi-weekly blood samples were collected from 95 African (Loxodonta africana and 75 Asian (Elephas maximus (8-55 years of age elephants over a 12-month period for analysis of serum progestogens and prolactin. Females were categorized as normal cycling (regular 13- to 17-week cycles, irregular cycling (cycles longer or shorter than normal or acyclic (baseline progestogens, <0.1 ng/ml throughout, and having Low/Normal (<14 or 18 ng/ml or High (≥14 or 18 ng/ml prolactin for Asian and African elephants, respectively. Rates of normal cycling, acyclicity and irregular cycling were 73.2, 22.5 and 4.2% for Asian, and 48.4, 37.9 and 13.7% for African elephants, respectively, all of which differed between species (P < 0.05. For African elephants, univariate assessment found that social isolation decreased and higher enrichment diversity increased the chance a female would cycle normally. The strongest multi-variable models included Age (positive and Enrichment Diversity (negative as important factors of acyclicity among African elephants. The Asian elephant data set was not robust enough to support multi-variable analyses of cyclicity status. Additionally, only 3% of Asian elephants were found to be hyperprolactinemic as compared to 28% of Africans, so predictive analyses of prolactin status were conducted on African elephants only. The strongest multi-variable model included Age (positive, Enrichment Diversity (negative, Alternate Feeding Methods (negative and Social Group Contact (positive as predictors of hyperprolactinemia. In summary, the incidence of ovarian cycle problems and hyperprolactinemia predominantly

  14. Effects of GnRH vaccination in wild and captive African Elephant bulls (Loxodonta africana on reproductive organs and semen quality.

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    Imke Lueders

    Full Text Available Although the African elephant (Loxodonta africana is classified as endangered by the International Union for Conservation of Nature (IUCN, in some isolated habitats in southern Africa, contraception is of major interest due to local overpopulation. GnRH vaccination has been promoted as a non-invasive contraceptive measure for population management of overabundant wildlife. We tested the efficacy of this treatment for fertility control in elephant bulls.In total, 17 male African elephants that were treated with a GnRH vaccine were examined in two groups. In the prospective study group 1 (n = 11 bulls, ages: 8-36 years, semen quality, the testes, seminal vesicles, ampullae and prostate, which were all measured by means of transrectal ultrasound, and faecal androgen metabolite concentrations were monitored over a three-year period. Each bull in the prospective study received 5 ml of Improvac® (1000 μg GnRH conjugate intramuscularly after the first examination, followed by a booster six weeks later and thereafter every 5-7 months. In a retrospective study group (group 2, n = 6, ages: 19-33 years, one examination was performed on bulls which had been treated with GnRH vaccine for 5-11 years.In all bulls of group 1, testicular and accessory sex gland sizes decreased significantly after the third vaccination. In six males examined prior to vaccination and again after more than five vaccinations, the testis size was reduced by 57.5%. Mean testicular height and length decreased from 13.3 ± 2.6 cm x 15.2 ± 2.8 cm at the beginning to 7.6 ± 2.1 cm x 10.2 ± 1.8 cm at the end of the study. Post pubertal bulls (>9 years, n = 6 examined prior to vaccination produced ejaculates with viable spermatozoa (volume: 8-175 ml, sperm concentration: 410-4000x106/ml, total motility: 0-90%, while after 5-8 injections, only 50% of these bulls produced ejaculates with a small number of immotile spermatozoa. The ejaculates of group 2 bulls (vaccinated >8 times were

  15. Using camera traps and digital video to investigate the impact of Aethina tumida pest on honey bee (Apis mellifera adansonii reproduction and ability to keep away elephants (Loxodonta africana cyclotis in Gamba, Gabon

    Directory of Open Access Journals (Sweden)

    Steeve Ngama

    2018-06-01

    Full Text Available Bees and elephant interactions are the core of a conservation curiosity since it has been demonstrated that bees, one of the smallest domesticated animals, can keep away elephants, the largest terrestrial animals. Yet, insects' parasites can impact the fitness and activity of the bees. Since their activity is critical to the repellent ability against elephants, this study assessed the impact of small hive beetles (Aethina tumida on bee (Apis mellifera adansonii reproduction and ability to keep forest elephants (Loxodonta africana cyclotis away. Because interspecies interactions are not easy to investigate, we have used camera traps and digital video to observe the activity of bees and their interactions with wild forest elephants under varying conditions of hive infestation with the small hive beetle, a common bee pest. Our results show that queen cells are good visual indicators of colony efficiency on keeping away forest elephants. We give evidences that small hive beetles are equivalently present in large and small bee colonies. Yet, results show no worries about the use of bees as elephant deterrents because of parasitism due to small hive beetles. Apis mellifera adansonii bees seem to effectively cope with small hive beetles showing no significant influence on its reproduction and ability to keep elephants away. This study also reports for the first time the presence of Aethina tumida as a constant beekeeping pest that needs to be addressed in Gabon.

  16. Intestinal protozoa of the African elephant Loxodonta africana ...

    African Journals Online (AJOL)

    The digestive tract of 15 elephants from South Africa and two from Zaïre were sampled in order to determine the identity, density and population composition of the intestinal protozoa. The following orders were represented: Gymnostomatida, Trichostomatida and Entodiniomorphida. Altogether 17 species were identified, ...

  17. Prosopis Africana SEEDS (OKPEYE)

    African Journals Online (AJOL)

    User

    Keywords: Prosopis africana, okpeye seeds, thermal heat conductivity, specific heat capacity, thermal heat diffusivity, .... 2.3 Determination of Thermal Properties of Prosopis. Africana .... and the guard ring was filled with fiber glass at both the.

  18. The Africana world

    DEFF Research Database (Denmark)

    It is 127 years since the Scramble for Africa divided up the continent, imposing borders that have led to conflict rather than peace and stability. It is 100 years since the African National Congress (ANC) was founded as the first African liberation movement with pan-African roots. It is nearly 50...... engagements with Africa's rich cultural heritage, its lingering contemporary challenges, its multifaceted systems of knowledge and its future in the exciting context of the twenty-first century. Africana World: From Fragmentation to Unity and Renaissance is put together in order to help develop the study...... and knowledge of African liberation across the continent and the diaspora. This first volume launches a new book series, following the Scramble for Africa conferences held every May to commemorate the founding of the OAU, which will be published annually to support the scholarly study of African unity...

  19. Ovulation, pregnancy, placentation and husbandry in the African elephant (Loxodonta africana)

    OpenAIRE

    Allen, W.R

    2006-01-01

    The African elephant reproduces so efficiently in the wild that overpopulation is now a serious problem in some game parks in Zimbabwe, Botswana and South Africa. The female reaches puberty between 10 and 12 years of age in the wild and, when in captivity, shows oestrous cycles of 14–15 weeks duration. She readily conceives a singleton in the wild yet her uterus has the capacity for twins. She shows a gestation length of 22 months and, in the wild, shows a population density and feed dependen...

  20. Patch-occupancy survey of elephant (Loxodonta africana surrounding Livingstone, Zambia

    Directory of Open Access Journals (Sweden)

    David A. Youldon

    2017-01-01

    Full Text Available Wild elephants represent the biggest human–wildlife conflict issue in Livingstone, Zambia. However, little is known about their movements. This survey investigated elephants’ habitat use outside a core protected and fenced zone that forms part of Mosi-oa-Tunya National Park, Zambia. Using ‘patch-occupancy’ methodology, indications of elephant presence (feeding behaviour, dung and tracks were surveyed. The survey aimed to assist proposed future monitoring exercises by defining the geographical extent that should be considered to improve accuracy in species abundance estimates. Results were supplemented using collected indications of elephant presence from prior monitoring exercises, and during this survey. Elephant presence was confirmed up to 8 km from the boundary of the protected core habitat, focussed in: (1 an unfenced zone of the national park, (2 along a road leading from the national park to the Dambwa Forest to the north and (3 along two rivers located to the west (Sinde River and east (Maramba River of the core area. Detection probability of elephant presence was high using these methods, and we recommend regular sampling to determine changes in habitat use by elephants, as humans continue to modify land-use patterns. Conservation implications: Identification of elephant ranging behaviour up to 8 km outside of the Mosi-oa-Tunya National Park in southern Zambia will assist in managing human– elephant conflict in the area, as well as in assessing this seasonal population’s abundance.

  1. Measuring positive and negative affect in the voiced sounds of African elephants (Loxodonta africana).

    Science.gov (United States)

    Soltis, Joseph; Blowers, Tracy E; Savage, Anne

    2011-02-01

    As in other mammals, there is evidence that the African elephant voice reflects affect intensity, but it is less clear if positive and negative affective states are differentially reflected in the voice. An acoustic comparison was made between African elephant "rumble" vocalizations produced in negative social contexts (dominance interactions), neutral social contexts (minimal social activity), and positive social contexts (affiliative interactions) by four adult females housed at Disney's Animal Kingdom®. Rumbles produced in the negative social context exhibited higher and more variable fundamental frequencies (F(0)) and amplitudes, longer durations, increased voice roughness, and higher first formant locations (F1), compared to the neutral social context. Rumbles produced in the positive social context exhibited similar shifts in most variables (F(0 )variation, amplitude, amplitude variation, duration, and F1), but the magnitude of response was generally less than that observed in the negative context. Voice roughness and F(0) observed in the positive social context remained similar to that observed in the neutral context. These results are most consistent with the vocal expression of affect intensity, in which the negative social context elicited higher intensity levels than the positive context, but differential vocal expression of positive and negative affect cannot be ruled out.

  2. Characterization of casein and alpha lactalbumin of African elephant (Loxodonta africana) milk.

    Science.gov (United States)

    Madende, M; Osthoff, G; Patterton, H-G; Patterton, H E; Martin, P; Opperman, D J

    2015-12-01

    The current research reports partial characterization of the caseins and α-lactalbumin (α-LA) of the African elephant with proposed unique structure-function properties. Extensive research has been carried out to understand the structure of the casein micelles. Crystallographic structure elucidation of caseins and casein micelles is not possible. Consequently, several models have been developed in an effort to describe the casein micelle, specifically of cow milk. Here we report the characterization of African elephant milk caseins. The κ-caseins and β-caseins were investigated, and their relative ratio was found to be approximately 1:8.5, whereas α-caseins were not detected. The gene sequence of β-casein in the NCBI database was revisited, and a different sequence in the N-terminal region is proposed. Amino acid sequence alignment and hydropathy plots showed that the κ-casein of African elephant milk is similar to that of other mammals, whereas the β-casein is similar to the human protein, and displayed a section of unique AA composition and additional hydrophilic regions compared with bovine caseins. Elephant milk is destabilized by 62% alcohol, and it is speculated that the β-casein characteristics may allow maintenance of the colloidal nature of the casein micelle, a role that was previously only associated with κ-casein. The oligosaccharide content of milk was reported to be low in dairy animals but high in some other species such as humans and elephants. In the milk of the African elephant, lactose and oligosaccharides both occur at high levels. These levels are typically related to the content of α-LA in the mammary gland and thus point to a specialized carbohydrate synthesis, where the whey protein α-LA plays a role. We report the characterization of African elephant α-LA. Homology modeling of the α-LA showed that it is structurally similar to crystal structures of other mammalian species, which in turn may be an indication that its functional properties, such as lactose synthesis, should not be impaired. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  3. Ovulation, pregnancy, placentation and husbandry in the African elephant (Loxodonta africana)

    Science.gov (United States)

    Allen, W.R

    2006-01-01

    The African elephant reproduces so efficiently in the wild that overpopulation is now a serious problem in some game parks in Zimbabwe, Botswana and South Africa. The female reaches puberty between 10 and 12 years of age in the wild and, when in captivity, shows oestrous cycles of 14–15 weeks duration. She readily conceives a singleton in the wild yet her uterus has the capacity for twins. She shows a gestation length of 22 months and, in the wild, shows a population density and feed dependent intercalving interval of 4–8 years. The trophoblast erodes the lumenal epithelium of the endometrium and stimulates upgrowths of blood vessel-containing stromal villi, which develop eventually into the broad, tightly folded lamellae of the zonary, endotheliochorial placenta. Significant quantities of leaked maternal erythrocytes and ferric iron are phagocytosed by specialized trophoblast cells in the haemophagous zones at the lateral edges of the placental band. Although the placenta itself is endocrinologically inert, the foetal gonads, which enlarge greatly during the second half of pregnancy can synthesize 5α-dihydryoprogesterone and other 5α pregnane derivatives from cholesterol and pregnenolone. These products may synergize with progestagens secreted by the 2–8 large corpora lutea which are always present in the maternal ovaries throughout gestation to maintain the pregnancy state. PMID:16627297

  4. Why do African elephants (Loxodonta africana) simulate oestrus? An analysis of longitudinal data.

    Science.gov (United States)

    Bates, Lucy A; Handford, Rosie; Lee, Phyllis C; Njiraini, Norah; Poole, Joyce H; Sayialel, Katito; Sayialel, Soila; Moss, Cynthia J; Byrne, Richard W

    2010-04-07

    Female African elephants signal oestrus via chemicals in their urine, but they also exhibit characteristic changes to their posture, gait and behaviour when sexually receptive. Free-ranging females visually signal receptivity by holding their heads and tails high, walking with an exaggerated gait, and displaying increased tactile behaviour towards males. Parous females occasionally exhibit these visual signals at times when they are thought not to be cycling and without attracting interest from musth males. Using demographic and behavioural records spanning a continuous 28-year period, we investigated the occurrence of this "simulated" oestrus behaviour. We show that parous females in the Amboseli elephant population do simulate receptive oestrus behaviours, and this false oestrus occurs disproportionately in the presence of naïve female kin who are observed coming into oestrus for the first time. We compare several alternative hypotheses for the occurrence of this simulation: 1) false oestrus has no functional purpose (e.g., it merely results from abnormal hormonal changes); 2) false oestrus increases the reproductive success of the simulating female, by inducing sexual receptivity; and 3) false oestrus increases the inclusive fitness of the simulating female, either by increasing the access of related females to suitable males, or by encouraging appropriate oestrus behaviours from female relatives who are not responding correctly to males. Although the observed data do not fully conform to the predictions of any of these hypotheses, we rule out the first two, and tentatively suggest that parous females most likely exhibit false oestrus behaviours in order to demonstrate to naïve relatives at whom to direct their behaviour.

  5. Development of the tush and tusk and tusklessness in African elephant (Loxodonta africana

    Directory of Open Access Journals (Sweden)

    E.J. Raubenheimer

    2000-07-01

    Full Text Available The embryologic development of the tush and tusk of the African elephant was studied by means of serial histologic sections prepared from elephant embryos with masses varying between Ig and 240 g. Statistics on tusklessness obtained during a four year population control programme in the Kruger National Park were analysed and compared with those reported in other elephant reserves in Southern Africa. Maxillae of eight elephant embryos, the maternal histories of which were available in six cases, were radiographed, dissected and examined microscopically. This study has shown that the tush and tusk develop from one tooth germ in a deciduous to permanent tooth relationship. Tusklessness was found to be unilateral or bilateral and associated with either the absence or presence of a tush. The possible causes of the differences in the frequency of bilateral tusklessness in different elephant populations are discussed.

  6. Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana.

    Science.gov (United States)

    Baines, Lydia; Morgan, Eric R; Ofthile, Mphoeng; Evans, Kate

    2015-04-01

    It is known from studies in a wide range of wild and domestic animals, including elephants, that parasites can affect growth, reproduction and health. A total of 458 faecal samples from wild elephants were analysed using a combination of flotation and sedimentation methods. Coccidian oocysts (prevalence 51%), and nematode (77%) and trematode (24%) eggs were found. Species were not identified, though trematode egg morphology was consistent with that of the intestinal fluke Protofasciola robusta. The following factors were found to have a significant effect on parasite infection: month, year, sex, age, and group size and composition. There was some evidence of peak transmission of coccidia and nematodes during the rainy season, confirmed for coccidia in a parallel study of seven sympatric domesticated elephants over a three month period. Nematode eggs were more common in larger groups and nematode egg counts were significantly higher in elephants living in maternal groups (mean 1116 eggs per gram, standard deviation, sd 685) than in all-male groups (529, sd 468). Fluke egg prevalence increased with increasing elephant age. Preservation of samples in formalin progressively decreased the probability of detecting all types of parasite over a storage time of 1-15 months. Possible reasons for associations between other factors and infection levels are discussed.

  7. Why do African elephants (Loxodonta africana simulate oestrus? An analysis of longitudinal data.

    Directory of Open Access Journals (Sweden)

    Lucy A Bates

    Full Text Available Female African elephants signal oestrus via chemicals in their urine, but they also exhibit characteristic changes to their posture, gait and behaviour when sexually receptive. Free-ranging females visually signal receptivity by holding their heads and tails high, walking with an exaggerated gait, and displaying increased tactile behaviour towards males. Parous females occasionally exhibit these visual signals at times when they are thought not to be cycling and without attracting interest from musth males. Using demographic and behavioural records spanning a continuous 28-year period, we investigated the occurrence of this "simulated" oestrus behaviour. We show that parous females in the Amboseli elephant population do simulate receptive oestrus behaviours, and this false oestrus occurs disproportionately in the presence of naïve female kin who are observed coming into oestrus for the first time. We compare several alternative hypotheses for the occurrence of this simulation: 1 false oestrus has no functional purpose (e.g., it merely results from abnormal hormonal changes; 2 false oestrus increases the reproductive success of the simulating female, by inducing sexual receptivity; and 3 false oestrus increases the inclusive fitness of the simulating female, either by increasing the access of related females to suitable males, or by encouraging appropriate oestrus behaviours from female relatives who are not responding correctly to males. Although the observed data do not fully conform to the predictions of any of these hypotheses, we rule out the first two, and tentatively suggest that parous females most likely exhibit false oestrus behaviours in order to demonstrate to naïve relatives at whom to direct their behaviour.

  8. Occurrence and seasonality of internal parasite infection in elephants, Loxodonta africana, in the Okavango Delta, Botswana

    Directory of Open Access Journals (Sweden)

    Lydia Baines

    2015-04-01

    Full Text Available It is known from studies in a wide range of wild and domestic animals, including elephants, that parasites can affect growth, reproduction and health. A total of 458 faecal samples from wild elephants were analysed using a combination of flotation and sedimentation methods. Coccidian oocysts (prevalence 51%, and nematode (77% and trematode (24% eggs were found. Species were not identified, though trematode egg morphology was consistent with that of the intestinal fluke Protofasciola robusta. The following factors were found to have a significant effect on parasite infection: month, year, sex, age, and group size and composition. There was some evidence of peak transmission of coccidia and nematodes during the rainy season, confirmed for coccidia in a parallel study of seven sympatric domesticated elephants over a three month period. Nematode eggs were more common in larger groups and nematode egg counts were significantly higher in elephants living in maternal groups (mean 1116 eggs per gram, standard deviation, sd 685 than in all-male groups (529, sd 468. Fluke egg prevalence increased with increasing elephant age. Preservation of samples in formalin progressively decreased the probability of detecting all types of parasite over a storage time of 1–15 months. Possible reasons for associations between other factors and infection levels are discussed.

  9. pacificus (Caridea) and Upogebia africana

    African Journals Online (AJOL)

    aemon pacificus and Upogebia africana in and out of .... bottom plankton samples were obtained using two 57-cm WP2 ... KAHLSICO model 005-W A 130 flowmeter. ..... Figure 7 Catch per unit effort of Pa/aemon paci/icus zoea 6 and adults.

  10. Cytotoxic glucosphingolipid from Celtis Africana.

    Science.gov (United States)

    Perveen, Shagufta; Al-Taweel, Areej Mohammad; Fawzy, Ghada Ahmed; El-Shafae, Azza Muhammed; Khan, Afsar; Proksch, Peter

    2015-05-01

    Literature survey proved the use of the powdered sun-dried bark and roots of Celtis africana for the treatment of cancer in South Africa. The aim of this study was to do further isolation work on the ethyl acetate fraction and to investigate the cytotoxic activities of the various fractions and isolated compound. Cytotoxicity of petroleum ether, chloroform, ethyl acetate, n-butanol fractions and compound 1 were tested on mouse lymphoma cell line L5178Y using the microculture tetrazolium assay. One new glucosphingolipid 1 was isolated from the aerial parts of C. africana. The structure of the new compound was determined by extensive analysis by one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy and mass spectrometry. The ethyl acetate fraction and compound 1 showed strong cytotoxic activity with an EC50 value of 8.3 μg/mL and 7.8 μg/mL, respectively, compared with Kahalalide F positive control (6.3 μg/mL). This is the first report of the occurrence of a cytotoxic glucosphingolipid in family Ulmaceae.

  11. Taxonomy Icon Data: African savanna elephant [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available African savanna elephant Loxodonta africana Chordata/Vertebrata/Mammalia/Theria/Eutheria/etc. Loxodonta_afri...cana_L.png Loxodonta_africana_NL.png Loxodonta_africana_S.png Loxodonta_africana_NS....png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+africana&t=L http://biosciencedbc.jp/taxonom...y_icon/icon.cgi?i=Loxodonta+africana&t=NL http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+afric...ana&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Loxodonta+africana&t=NS ...

  12. Physico-chemical and toxicological studies on Afzelia africana seed ...

    African Journals Online (AJOL)

    USER

    2010-03-29

    Mar 29, 2010 ... Table 2. Physico-chemical characteristics of Afzelia africana seed oil*. Property .... The moisture level of the seeds of A. africana is low resulting in low acid .... Keay RWJ, Onochie CFA, Stanfield DP (1964). Nigerian Trees, 2.

  13. Dietary management, husbandry, and body weights of African elephants (Loxodonta africana) during successful pregnancies at Disney's Animal Kingdom.

    Science.gov (United States)

    Sullivan, Kathleen; Kerr, Katherine; Wanty, Rachel; Amaral, Bryan; Olea-Popelka, Francisco; Valdes, Eduardo

    2016-11-01

    Successful pregnancy in African elephants is influenced by biological and environmental factors. For managed elephants many of these factors are set directly or indirectly by their human care takers, including nutrition and husbandry. While African elephants often struggle to conceive and produce healthy offspring under human care, Disney's Animal Kingdom (DAK) has effectively managed six gestations to fruition in three cows. Despite differences between mothers in terms of BW and growth curves during gravidity, each pregnancy successfully resulted in the birth of a healthy calf. Body weight (BW) gain during pregnancy ranged from 245 to 558 kg. Obesity in elephants is associated with increased occurrence of dystocia and mortality of the fetus and mother, hence understanding normal weight gains is an integral concept. Diet (dry matter basis) included high levels of fiber throughout pregnancies (60-70% neutral detergent fiber), vitamin E supplementation (116-214 mg/kg diet of alpha-tocopherol), as well as low levels of starch (2.5-5.1%) and crude fat (1.9-2.4%). Caretaker directed exercise during pregnancy at DAK served to prevent ventral edema, and increase muscle tone to prepare cows for parturition. Demonstrating techniques for effective care of pregnant females, as well as normal growth curves and fluctuations under ex situ conditions are necessary for future positive outcomes. Ensuring reproductive success through proper husbandry and nutrition are a key to long-term conservation of elephants. Zoo Biol. 35:574-578, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  14. Evaluation of Demographics and Social Life Events of Asian (Elephas maximus and African Elephants (Loxodonta africana in North American Zoos.

    Directory of Open Access Journals (Sweden)

    Natalia A Prado-Oviedo

    Full Text Available This study quantified social life events hypothesized to affect the welfare of zoo African and Asian elephants, focusing on animals that were part of a large multi-disciplinary, multi-institutional elephant welfare study in North America. Age was calculated based on recorded birth dates and an age-based account of life event data for each elephant was compiled. These event histories included facility transfers, births and deaths of offspring, and births and deaths of non-offspring herd mates. Each event was evaluated as a total number of events per elephant, lifetime rate of event exposure, and age at first event exposure. These were then compared across three categories: species (African vs. Asian; sex (male vs. female; and origin (imported vs. captive-born. Mean age distributions differed (p<0.05 between the categories: African elephants were 6 years younger than Asian elephants, males were 12 years younger than females, and captive-born elephants were 20 years younger than imported elephants. Overall, the number of transfers ranged from 0 to 10, with a 33% higher age-adjusted transfer rate for imported African than imported Asian elephants, and 37% lower rate for imported females than males (p<0.05. Other differences (p<0.05 included a 96% higher rate of offspring births for captive-born females than those imported from range countries, a 159% higher rate of birthing event exposures for captive-born males than for their imported counterparts, and Asian elephant females being 4 years younger than African females when they produced their first calf. In summarizing demographic and social life events of elephants in North American zoos, we found both qualitative and quantitative differences in the early lives of imported versus captive-born elephants that could have long-term welfare implications.

  15. Effects of daily management changes on behavioral patterns of a solitary female African elephant (Loxodonta africana) in a zoo.

    Science.gov (United States)

    Koyama, Nao; Ueno, Yoshikazu; Eguchi, Yusuke; Uetake, Katsuji; Tanaka, Toshio

    2012-07-01

    This study investigated the effects of changes in daily management on behavior of a solitary female elephant in a zoo. The activity budget and space utilization of the subject and the management changes were recorded for 1 year after the conspecific male died. The observation days could be categorized into five clusters (C1-C5) by the characteristic behavioral pattern of each day. C1 had the highest percentage of resting of all clusters, and was observed after the loss of the conspecific and the beginning of use of the indoor exhibition room at night. C2, which had the highest percentage of stereotypy of any cluster, was observed after the beginning of habituation to the indoor exhibition room. Also, when the time schedule of management was changed irregularly, the subject frequently exhibited stereotypic pacing (C2, C4). The subject tended to rest when exhibiting lameness in the left hind limb (C3). In C5, activity reached a high level when she could utilize a familiar place under a stable management schedule. These results indicate that management changes affected the mental stability of an elephant in the early stage of social isolation. © 2012 The Authors. Animal Science Journal © 2012 Japanese Society of Animal Science.

  16. Development of the tush and tusk and tusklessness in African elephant (Loxodonta africana)

    OpenAIRE

    E.J. Raubenheimer

    2000-01-01

    The embryologic development of the tush and tusk of the African elephant was studied by means of serial histologic sections prepared from elephant embryos with masses varying between Ig and 240 g. Statistics on tusklessness obtained during a four year population control programme in the Kruger National Park were analysed and compared with those reported in other elephant reserves in Southern Africa. Maxillae of eight elephant embryos, the maternal histories of which were available in six case...

  17. Tuberculosis serosurveillance and management practices of captive African elephants (Loxodonta africana) in the Kavango-Zambezi Transfrontier Conservation Area.

    Science.gov (United States)

    Rosen, L E; Hanyire, T G; Dawson, J; Foggin, C M; Michel, A L; Huyvaert, K P; Miller, M A; Olea-Popelka, F J

    2018-04-01

    Transfrontier conservation areas represent an international effort to encourage conservation and sustainable development. Their success faces a number of challenges, including disease management in wildlife, livestock and humans. Tuberculosis (TB) affects humans and a multitude of non-human animal species and is of particular concern in sub-Saharan Africa. The Kavango-Zambezi Transfrontier Conservation Area encompasses five countries, including Zimbabwe, and is home to the largest contiguous population of free-ranging elephants in Africa. Elephants are known to be susceptible to TB; thus, understanding TB status, exposure and transmission risks to and from elephants in this area is of interest for both conservation and human health. To assess risk factors for TB seroprevalence, a questionnaire was used to collect data regarding elephant management at four ecotourism facilities offering elephant-back tourist rides in the Victoria Falls area of Zimbabwe. Thirty-five working African elephants were screened for Mycobacterium tuberculosis complex antibodies using the ElephantTB Stat-Pak and the DPP VetTB Assay for elephants. Six of 35 elephants (17.1%) were seropositive. The risk factor most important for seropositive status was time in captivity. This is the first study to assess TB seroprevalence and risk factors in working African elephants in their home range. Our findings will provide a foundation to develop guidelines to protect the health of captive and free-ranging elephants in the southern African context, as well as elephant handlers through simple interventions. Minimizing exposure through shared feed with other wildlife, routine TB testing of elephant handlers and regular serological screening of elephants are recommended as preventive measures. © 2017 Blackwell Verlag GmbH.

  18. SPATIAL VARIABILITY IN THE MUDPRAWN UPOGEBIA AFRICANA ...

    African Journals Online (AJOL)

    A nested sampling design was used to examine the variability in density, biomass, sex ratio and size of the estuarine mudprawn Upogebia africana in six estuaries on the south-east coast of South Africa. The objectives were to test the general hypothesis that there is variability in these variables at the scales of regions, ...

  19. Africana-womanism and the sexist paradox in Emeka Nwabueze's ...

    African Journals Online (AJOL)

    Nwabueze's The Dragon's Funeral, which examines the remote factors that triggered the Aba women's riot, sounds Africana-womanist largely because it adopts a moderate approach in reviewing the relationship between men and women in a male dominated society. Africana-womanism, isolates the black peculiarity of the ...

  20. INTEGRAÇÃO AFRICANA: DA ORGANIZAÇÃO DA UNIDADE AFRICANA À UNIÃO AFRICANA

    OpenAIRE

    Diallo, Alfa Oumar

    2015-01-01

    Desde Kwamé N´Krumah a unidade da África era um grande desejo. A Organização da Unidade Africana (OUA) servia aos olhares de alguns na pobreza moral e material do continente. Destaca-se, que dentro da OUA, alguns fundadores militavam em favor da instituição dos Estados Unidos da África enquanto que outros pregavam, ao contrário, pela fragmentação dos Estados-Nações sob uma forma organizacional. Os Estados Unidos da África certamente seriam limitados à exploração contínua deste continente, mas...

  1. Allelotoxicity of Oudneya africana R. Br. aqueous leachate on ...

    African Journals Online (AJOL)

    This present study was conducted to investigate the possible allelopathic effect of Oudneya africana (donor species) on Bromus tectorum (weed species) and Triticum aestivum (cv. Sahel1; crop species) through germination bioassay experiment. B. tectorum is a winter annual grass that grows in winter wheat and other ...

  2. empirical study of the characteristics of afzelia africana seed under

    African Journals Online (AJOL)

    HP

    significant probably because of the thick seed coat. True density did not show a consistent variation with change in moisture content. 3.2 Mechanical Properties. The mechanical properties study was conducted using the data obtained from the compressive loading of the. Afzelia Africana seeds in a monsan to tensiometer.

  3. Effect of supplementation of African breadfruit (Treculia africana ...

    African Journals Online (AJOL)

    African breadfruit (Treculia africana) hulls were supplemented at different levels with other organic food processing wastes (orange, plantain, cassava and soybean). Optimum supplementation of 40:60 (breadfruit hulls to each waste) was obtained. Proximate and mineral composition of the unsupplemented and the ...

  4. Allelochemicals Effect of Aqueous Leachate from Oudneya Africana R

    African Journals Online (AJOL)

    nesrine

    2014-03-05

    Mar 5, 2014 ... This present study was conducted to investigate the possible allelopathic effect of Oudneya africana. (donor species) on Bromus tectorum (weed species) and Triticum aestivum (cv. Sahel1; crop species) through germination bioassay experiment. B. tectorum is a winter annual grass that grows in winter.

  5. Kinetics of saponification of Treculia africana oil using a locally ...

    African Journals Online (AJOL)

    The investigation on the saponification of Treculia africana (breadfruit) oil using a locally obtained alkaline (Ngu) extracted from the burnt female inflorescence of oil palm bunch using kinetic approach proved successful and showed a high probability of producing good quality toilet soap. The result obtained revealed that ...

  6. Clinical and Parasitological Effects of Aspilia africana (Pers.)

    African Journals Online (AJOL)

    Department of Pharmacy, Makerere University

    extract possessed in vitro antiplasmodial activity (IC50 30µg/ml) but no remarkable cytotoxicity. The A. africana preparation shows potential ... procedure employed by the traditional healers. For this purpose 5-10 tablespoonfuls of .... alkaloids, tannins and traces of essential oils. 1 - cpm in treated in untreated cultures x 100 ...

  7. Assessment of Toxicity Profile of Lasianthera Africana Leaf ...

    African Journals Online (AJOL)

    ALICE

    2015-04-15

    Apr 15, 2015 ... intraperitoneal, intravenous or intramuscular routes of .... Effect of oral administration of doses of Lasianthera africana leaf extract on body weight of normal rat ... drinking water and treated with metformin (anti-diabetic drug) at a dose level ... glucometer (One Touch Ultra 2 Blood Glucose Monitoring System,.

  8. Afzelia africana , A Novel Non Starch Polysaccharide, Raised ...

    African Journals Online (AJOL)

    The effects o vegetable flour prepared from indigenous plant Afzelia africana, a legume, on the fasting plasma cholesterol and triglyceride levels of rats were investigated. Chemical analysis indicated that Afzelia flour contained significant amount of non-starch polysaccharides (NSP). The flour of Afzelia was incorporated ...

  9. in-vitro antimicrobial properties of aspilla africana (compositae).

    African Journals Online (AJOL)

    Dr Olaleye

    The in vitro anti-microbial activity of the petroleum ether, chloroform and methanol extracts of Aspilia africana. (Compositae) was studied. The bacterial used for the antimicrobial analysis consisted of 3 clinical strains of. Staphylococcus aureus, Bacillus subtilis, 2 clinical strains of Escherichia coli and Pseudomonas ...

  10. In-vitro antimicrobial properties of Aspilla africana (compositae ...

    African Journals Online (AJOL)

    ... more active than the soxhlet extracts. Only the cold petroleum ether extract showed a good activity against both C. albicans and A. flavus. The phytochemical screening for the whole plat of A. africana revealed the presence of alkaloids, saponin glycosides and tannins but absence of steroidal nucleus and anthraquinone.

  11. Socio-economic contribution of African breadfruit ( Treculia africana ...

    African Journals Online (AJOL)

    The Non-Timber Forest Products (NTFPs) the conserve are gathered for household consumption and commercial uses; they have formed an inherent part of rural ... the level of income generation, processing, distribution of sales as well as the importance of Treculia africana to food security in Southeastern, Nigeria in 2015.

  12. Nuclear microprobe studies of elemental distributions in dormant seeds of Burkea africana

    Science.gov (United States)

    Witkowski, E. T. F.; Weiersbye-Witkowski, I. M.; Przybyłowicz, W. J.; Mesjasz-Przybyłowicz, J.

    1997-07-01

    Seed nutrient stores are vital post-germination for the establishment of seedlings in harsh and unpredictable environments. Plants of nutrient-poor environments allocate a substantial proportion of total acquired nutrients to reproduction (i.e. seeds). We propose that differential allocation of mineral resources to specific seed tissues is an indication of a species germination and establishment strategy. Burkea africana Hook is a leguminous tree typical of broad-leaved nutrient-poor savannas in southern Africa. Elemental distributions in dormant B. africana seed structures were obtained using the true elemental imaging system (Dynamic Analysis) of the NAC Van de Graaff nuclear microprobe. Raster scans of 3.0 MeV protons were complemented by simultaneous BS and PIXE point analyses. Mineral nutrient concentrations varied greatly between seed tissues. Elevated levels of metals known to play an important role as plant enzyme co-factors were found in the seed lens and embryonic axis. Distributions of most of these metals (Ca, Mn, Fe and Zn, but not K or Cu) were positively correlated with embryonic P distribution, and probably represent phytin deposits. The distribution of metals within seed structures is 'patchy' due to their complexation with P as electron-dense globoid phytin crystals, which constrains the interpretation of PIXE point analyses.

  13. Antioxidative, anti-inflammatory potentials and phytochemical profile of Commiphora africana (A. Rich. Engl. (Burseraceae and Loeseneriella africana (Willd. (Celastraceae stem leaves extracts

    Directory of Open Access Journals (Sweden)

    Moussa Compaoré

    2016-08-01

    Conclusions: The present study may explain the effectiveness of plants in traditional medicine of Burkina Faso, singularly Commiphora africana and Loeseneriella africana. The next investigation was to sub-fractionate the methanol fraction in order to isolate new antioxidant and/or anti-inflammatory compounds.

  14. Fermentation of Agave tequilana juice by Kloeckera africana: influence of amino-acid supplementations.

    Science.gov (United States)

    Valle-Rodríguez, Juan Octavio; Hernández-Cortés, Guillermo; Córdova, Jesús; Estarrón-Espinosa, Mirna; Díaz-Montaño, Dulce María

    2012-02-01

    This study aimed to improve the fermentation efficiency of Kloeckera africana K1, in tequila fermentations. We investigated organic and inorganic nitrogen source requirements in continuous K. africana fermentations fed with Agave tequilana juice. The addition of a mixture of 20 amino-acids greatly improved the fermentation efficiency of this yeast, increasing the consumption of reducing sugars and production of ethanol, compared with fermentations supplemented with ammonium sulfate. The preference of K. africana for each of the 20 amino-acids was further determined in batch fermentations and we found that asparagine supplementation increased K. africana biomass production, reducing sugar consumption and ethanol production (by 30, 36.7 and 45%, respectively) over fermentations supplemented with ammonium sulfate. Therefore, asparagine appears to overcome K. africana nutritional limitation in Agave juice. Surprisingly, K. africana produced a high concentration of ethanol. This contrasts to poor ethanol productivities reported for other non-Saccharomyces yeasts indicating a relatively high ethanol tolerance for the K. africana K1 strain. Kloeckera spp. strains are known to synthesize a wide variety of volatile compounds and we have shown that amino-acid supplements influenced the synthesis by K. africana of important metabolites involved in the bouquet of tequila. The findings of this study have revealed important nutritional limitations of non-Saccharomyces yeasts fermenting Agave tequilana juice, and have highlighted the potential of K. africana in tequila production processes.

  15. Imagens e palavras: suas correspondências na arte africana

    OpenAIRE

    Maria Corina Rocha

    2007-01-01

    Esta dissertação constitui-se da pesquisa e do estudo bibliográfico sobre cultura material e arte africana tradicional, aqui entendida como a arte de origem anterior ao período da colonização européia, antes do século XIX, mas também a produzida durante este período, especificamente a arte da África central. Nossa pesquisa reflete o fato de haver no Brasil uma omissão considerável de fontes bibliográficas e de informações específicas sobre arte e cultura material africana em língua portuguesa...

  16. Uncommon mandibular osteomyelitis in a cat caused by Nocardia africana

    Directory of Open Access Journals (Sweden)

    de Farias Marconi

    2012-12-01

    Full Text Available Abstract Background Nocardiosis is an unusual infection in companion animals characterized by suppurative to pyogranulomatous lesions, localized or disseminated. Cutaneous-subcutaneous, pulmonary and systemic signs are observed in feline nocardiosis. However, osteomyelitis is a rare clinical manifestation in cats. Nocardia cyriacigeorgica (formerly N. asteroides sensu stricto, Nocardia brasiliensis, Nocardia otitidiscaviarum, and Nocardia nova are the most common pathogenic species identified in cats, based on recent molecular classification (16S rRNA gene. The present report is, to our knowledge, the first case of mandibular osteomyelitis in a cat caused by Nocardia africana, diagnosed based upon a combination of methods, including molecular techniques. Case presentation A one-year-old non-neutered female cat, raised in a rural area, was admitted to the Companion Animal Hospital-PUCPR, São José dos Pinhais, State of Paraná, Brazil, with a history a progressive facial lesion, difficulty apprehending food, loss of appetite, apathy and emaciation. Clinical examination showed fever, submandibular lymphadenitis, and a painless, 8 cm diameter mass, which was irregularly-shaped, of firm consistency, and located in the region of the left mandible. The skin around the lesion was friable, with diffuse inflammation (cellulitis, multiple draining sinuses, and exudation of serosanguinous material containing whitish “sulfur” granules. Diagnosis was based initially in clinical signs, microbiological culture, cytological, and histopathological findings, and radiographic images. Molecular sequencing of 16S rRNA of isolate allowed diagnosis of Nocardia africana. Despite supportive care and antimicrobial therapy based on in vitro susceptibility testing the animal died. Conclusion The present report describes a rare clinical case of feline osteomyelitis caused by Nocardia africana, diagnosed based upon a combination of clinical signs, microbiological

  17. Uncommon mandibular osteomyelitis in a cat caused by Nocardia africana.

    Science.gov (United States)

    de Farias, Marconi Rodrigues; Werner, Juliana; Ribeiro, Márcio Garcia; Rodigheri, Sabrina Marin; Cavalcante, Carolina Zaghi; Chi, Kung Darh; Condas, Larissa Anuska Zeni; Gonoi, Tohru; Matsuzama, Tetsuhiro; Yazama, Katsukiyo

    2012-12-06

    Nocardiosis is an unusual infection in companion animals characterized by suppurative to pyogranulomatous lesions, localized or disseminated. Cutaneous-subcutaneous, pulmonary and systemic signs are observed in feline nocardiosis. However, osteomyelitis is a rare clinical manifestation in cats. Nocardia cyriacigeorgica (formerly N. asteroides sensu stricto), Nocardia brasiliensis, Nocardia otitidiscaviarum, and Nocardia nova are the most common pathogenic species identified in cats, based on recent molecular classification (16S rRNA gene). The present report is, to our knowledge, the first case of mandibular osteomyelitis in a cat caused by Nocardia africana, diagnosed based upon a combination of methods, including molecular techniques. A one-year-old non-neutered female cat, raised in a rural area, was admitted to the Companion Animal Hospital-PUCPR, São José dos Pinhais, State of Paraná, Brazil, with a history a progressive facial lesion, difficulty apprehending food, loss of appetite, apathy and emaciation. Clinical examination showed fever, submandibular lymphadenitis, and a painless, 8 cm diameter mass, which was irregularly-shaped, of firm consistency, and located in the region of the left mandible. The skin around the lesion was friable, with diffuse inflammation (cellulitis), multiple draining sinuses, and exudation of serosanguinous material containing whitish "sulfur" granules.Diagnosis was based initially in clinical signs, microbiological culture, cytological, and histopathological findings, and radiographic images. Molecular sequencing of 16S rRNA of isolate allowed diagnosis of Nocardia africana. Despite supportive care and antimicrobial therapy based on in vitro susceptibility testing the animal died. The present report describes a rare clinical case of feline osteomyelitis caused by Nocardia africana, diagnosed based upon a combination of clinical signs, microbiological culture, cytological and histopathological findings, radiographic images, and

  18. As literaturas africanas de língua portuguesa

    Directory of Open Access Journals (Sweden)

    Pires Laranjeira

    2000-03-01

    Full Text Available O autor traça o percurso genérico das literaturas africanas de língua portuguesa, nos últimos ISO a nos, mostrando como os movimentos, revistas e obras se foram pautando, cada vez mais intensamente, pela busca da identidade própria, autonômica, nacional, dentro da língua comum e de heranças culturais diversas. De entre essas heranças, destacam-se o Modernismo, o Neo-rea lismo, a Negritude ou o romance social do Nordeste brasileiro. Mas, fundamentalmente, as literaturasafri canas formaram-se como nacionais, antes da nacionalidade, através de uma retórica e uma imagética que enfa tizavam o concreto, o social, a história e o político.

  19. Antioxidative, anti-inflammatory potentials and phytochemical profile of Commiphora africana(A. Rich.) Engl.(Burseraceae) and Loeseneriella africana(Willd.)(Celastraceae) stem leaves extracts

    Institute of Scientific and Technical Information of China (English)

    Moussa Compaoré; Roland Ng-Tiéro Meda; Sahabi Bakasso; Laurian Vlase; Martin Kiendrebeogo

    2016-01-01

    Objective: To assess the antioxidant and anti-inflammatory activities as well as to determine the flavonoids and phenolic acids content of active fractions.Methods: Two medicinal plant samples were extracted successively in Soxhlet apparatus with n-hexane, dichloromethane, acetonitrile, ethyl acetate, methanol and n-butanol. Five methods were used to evaluate the antioxidant activity. Anti-inflammatory activity was done through the inhibition of the cyclooxygenase enzymes(COX-1 and COX-2).Polyphenolic compounds were analyzed by using a spectrophotometrical and high performance liquid chromatography-mass spectrometry(HPLC-MS) methods.Results: The data showed that the stem leaves extracts of Commiphora africana and Loeseneriella africana possessed significant in vitro antioxidant and anti-inflammatory activities. Polar extracts had radical scavenging effects and they reduced iron(III). The prostaglandin production was significantly stopped by acetonitrile and methanol extracts.These biological activities were supported by some bioactive compounds quantified by using the HPLC-MS. p-Coumaric acid, ferulic acid, isoquercitrin, quercitrin, quercetin,rutin, kaempferol and apigenin were the most metabolites quantified.Conclusions: The present study may explain the effectiveness of plants in traditional medicine of Burkina Faso, singularly Commiphora africana and Loeseneriella africana.The next investigation was to sub-fractionate the methanol fraction in order to isolate new antioxidant and/or anti-inflammatory compounds.

  20. Impact of fresh and saline water flooding on leaf gas exchange in two Italian provenances of Tamarix africana Poiret.

    Science.gov (United States)

    Abou Jaoudé, R; de Dato, G; Palmegiani, M; De Angelis, P

    2013-01-01

    In Mediterranean coastal areas, changes in precipitation patterns and seawater levels are leading to increased frequency of flooding and to salinization of estuaries and freshwater systems. Tamarix spp. are often the only woody species growing in such environments. These species are known for their tolerance to moderate salinity; however, contrasting information exists regarding their tolerance to flooding, and the combination of the two stresses has never been studied in Tamarix spp. Here, we analyse the photosynthetic responses of T. africana Poiret to temporary flooding (45 days) with fresh or saline water (200 mm) in two Italian provenances (Simeto and Baratz). The measurements were conducted before and after the onset of flooding, to test the possible cumulative effects of the treatments and effects on twig aging, and to analyse the responses of twigs formed during the experimental period. Full tolerance was evident in T. africana with respect to flooding with fresh water, which did not affect photosynthetic performances in either provenance. Saline flooding was differently tolerated by the two provenances. Moreover, salinity tolerance differently affected the two twig generations. In particular, a reduction in net assimilation rate (-48.8%) was only observed in Baratz twigs formed during the experimental period, compared to pre-existing twigs. This reduction was a consequence of non-stomatal limitations (maximum carboxylation rate and electron transport), probably as a result of higher Na transport to the twigs, coupled with reduced Na storage in the roots. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  1. Effect of Methanol extract of Kigelia africana on Sperm Motility and ...

    African Journals Online (AJOL)

    The fertility activities of the fruit of Kigelia africana Lam. Benth. Family Bignoniaceae, a medicinal plant used in south eastern Nigeria by local traditional healers for treatment of fertility abnormalities especially in male and female adults has been carried out. The research revealed that male rats treated with the methanol ...

  2. Basic Density and Strength Properties Variations in Cordia Africana (Lam) Grown Under Agroforestry in Arumeru, Tanzania

    NARCIS (Netherlands)

    Mahonge, C.P.I.

    2007-01-01

    Variations in basic density and strength properties of Cordia africana (lam) grown under agroforestry in Arumeru district Arusha Tanzania were determined. Tree sampling procedure and data collection based on standard methods (ISO 3129.of 1975). The main results indicated that basic density increased

  3. ConsciÃncia Corporal e Ancestralidade Africana: Conceitos SociopoÃticos Produzidos por Pessoas de Santo

    OpenAIRE

    Norval Batista Cruz

    2009-01-01

    Este estudo apresenta os conceitos sociopoÃticos produzidos por uma comunidade de terreiro de candomblÃ, Ilà Axà Omo TifÃ, localizada no bairro de Jangurussu, na periferia de Fortaleza-Ce. O tema gerador da pesquisa à consciÃncia corporal e ancestralidade africana. Noto que, apesar dos terreiros de candomblÃ, em principio estarem mais conectados com a cultura de matriz africana, nem sempre se encontra uma prÃtica de consciÃncia corporal associada à ancestralidade africana e Ãs vezes, hà uma d...

  4. Power, policy and the Prunus africana bark trade, 1972-2015.

    Science.gov (United States)

    Cunningham, A; Anoncho, V F; Sunderland, T

    2016-02-03

    After almost 50 years of international trade in wild harvested medicinal bark from Africa and Madagascar, the example of Prunus africana holds several lessons for both policy and practice in the fields of forestry, conservation and rural development. Due to recent CITES restrictions on P. africana exports from Burundi, Kenya and Madagascar, coupled with the lifting of the 2007 European Union (EU) ban in 2011, Cameroon's share of the global P. africana bark trade has risen from an average of 38% between 1995 and 2004, to 72.6% (658.6 metric tons) in 2012. Cameroon is therefore at the center of this international policy arena. This paper draws upon several approaches, combining knowledge in working with P. africana over a 30-year period with a thorough literature review and updated trade data with "ground-truthing" in the field in 2013 and 2014. This enabled the construction of a good perspective on trade volumes (1991-2012), bark prices (and value-chain data) and the gaps between research reports and practice. Two approaches provided excellent lenses for a deeper understanding of policy failure and the "knowing-doing gap" in the P. africana case. A similar approach to Médard's (1992) analyses of power, politics and African development was taken and secondly, studies of commodity chains that assess the power relations that coalesce around different commodities (Ribot, 1998; Ribot and Peluso, 2003). Despite the need to conserve genetically and chemically diverse P. africana, wild populations are vulnerable, even in several "protected areas" in Burundi, Cameroon, the Democratic Republic of Congo and in the forest reserves of Madagascar. Secondly, hopes of decentralized governance of this forest product are misplaced due to elite capture, market monopolies and subsidized management regimes. At the current European price, for P. africana bark (US$6 per kg) for example, the 2012 bark quota (658.675t) from Cameroon alone was worth over US$3.9 million, with the majority of

  5. Use of wood anatomy to identify poisonous plants: Charcoal of Spirostachys africana

    Directory of Open Access Journals (Sweden)

    Sandra J. Lennox

    2015-03-01

    Full Text Available Spirostachys africana Sond. (tamboti/tambotie is a woodland tree that is often found near water. It has a poisonous and purgative latex. The archaeological site of Sibudu, a rock shelter in KwaZulu-Natal, has evidence, from well-preserved charcoal and seeds, of past environments and wood use from approximately 77–38 thousand years ago (ka. As their uses and environmental indicators are different, it is critical to confidently distinguish among the three anatomically similar woods of the Euphorbiaceae: Spirostachys africana, Sclerocroton integerrimus and Shirakiopsis elliptica. A detailed anatomical study of reference and archaeological charcoal shows that xylem vessel width increases proportionally as vessel frequency decreases, from Spirostachys africana, Sclerocroton integerrimus to Shirakiopsis elliptica. Crystals of calcium oxalate are present in ray cells of Spirostachys africana, whereas silica bodies are present in ray cells of Sclerocroton integerrimus and Shirakiopsis elliptica. Using these features, the presence of Spirostachys africana was confirmed amongst hearth charcoal of the Spotty Camel layer, with an age of approximately 58 ka and of the Mottled Deposit occupational layer, with an age of approximately 49 ka. The presence of this charcoal, collected from ancient fireplaces or sieved from surrounding sediments, implies that people at Sibudu understood and used this poisonous tree to their advantage. We are encouraged in this view by the presence of many Cryptocarya woodii leaves found on the surface of 77-ka sedge bedding at Sibudu (Wadley L et al., Science. 2011;334:1388–1391. Cryptocarya woodii has insecticidal and larvacidal properties and members of the Laurel family are well known for their medicinal properties.

  6. Antimicrobial, Antioxidant, and Wound Healing Properties of Kigelia africana (Lam. Beneth. and Strophanthus hispidus DC.

    Directory of Open Access Journals (Sweden)

    Christian Agyare

    2013-01-01

    Full Text Available Microbial infections of various types of wounds are a challenge to the treatment of wounds and wound healing. The study was to investigate antimicrobial and antioxidant properties of methanol leaf and stem bark extracts of Kigelia africana and methanol leaf and root extracts of Strophanthus hispidus and also to determine wound healing properties of the extracts. The antimicrobial activities of the methanol extracts were determined against two Gram-positive and two Gram-negative bacteria and a fungus using agar diffusion and micro-dilution methods. The antioxidant activity was determined using 1,1-diphenyl-2-picryl–hydrazyl (DPPH method. The influence of the extracts on rate of wound closure was investigated using the excision wound model and histopathological investigation of treated and untreated wound tissues performed. The MICs of leaf extract of K. africana against test organisms were 2.5–7.5 mg/mL and stem bark extract were 2.25–7.5 mg/mL. The leaf extract of S. hispidus had MIC range of 2.5–7.5 mg/mL and 2.5–10 mg/mL for root extract. The IC50 of leaf and stem bark extracts of K. africana were 56.9 and 13.7 μg/mL, respectively and leaf and root of S. hispidus were 49.8 and 45.1 μg/mL, respectively. K. africana extracts (7.5% w/w showed significant ( wound contraction at day 7 with 72% of wound closure whiles significant ( wound contractions were observed on day 11 for stem bark of K. africana, leaf and root extracts of S. hispidus. Wound tissues treated with the extracts showed improved collagenation, re-epitheliazition and rapid granulation formation compared with untreated wound tissues. The extracts were found to contain alkaloids, saponins, tannins, flavonoids, carbohydrates, and sapogenetic glycosides. The HPLC finger-printing of the extracts were developed. The leaf, stem bark and root extracts of K. africana and S. hispidus exhibited antimicrobial, antioxidant, and enhanced wound healing properties and these

  7. Using camera traps and digital video to investigate the impact of Aethina tumida pest on honey bee (Apis mellifera adansonii) reproduction and ability to keep away elephants (Loxodonta africana cyclotis) in Gamba, Gabon

    OpenAIRE

    Steeve Ngama; Lisa Korte; Mireille Johnson; Jérôme Bindelle; Auguste Ndoutoume Ndong; Cédric Vermeulen

    2018-01-01

    Bees and elephant interactions are the core of a conservation curiosity since it has been demonstrated that bees, one of the smallest domesticated animals, can keep away elephants, the largest terrestrial animals. Yet, insects' parasites can impact the fitness and activity of the bees. Since their activity is critical to the repellent ability against elephants, this study assessed the impact of small hive beetles (Aethina tumida) on bee (Apis mellifera adansonii) reproduction and ability to k...

  8. Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana) treated with a gonadotropin-releasing hormone (GnRH) vaccine for inducing anoestrus.

    Science.gov (United States)

    Benavides Valades, Gabriela; Ganswindt, Andre; Annandale, Henry; Schulman, Martin L; Bertschinger, Henk J

    2012-08-25

    In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows. Between May 2009-June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM) on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac®, Pfizer Animal Health, Sandton, South Africa) 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP) vaccine for four years (2004-2007). All 12 monitored females (8 treated and 4 controls) showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces) were significantly higher (Pelephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls.

  9. Non-invasive assessment of the reproductive cycle in free-ranging female African elephants (Loxodonta africana treated with a gonadotropin-releasing hormone (GnRH vaccine for inducing anoestrus

    Directory of Open Access Journals (Sweden)

    Benavides Valades Gabriela

    2012-08-01

    Full Text Available Abstract Background In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows. Methods Between May 2009 - June 2010, luteal activity of 12 elephant cows was monitored non-invasively using an enzyme immunoassay detecting faecal 5alpha-reduced pregnanes (faecal progestagen metabolites, FPM on a private game reserve in South Africa. No bulls of breeding age were present on the reserve prior to and for the duration of the study. After a 3-month control period, 8 randomly-selected females were treated twice with 600 micrograms of GnRH vaccine (Improvac®, Pfizer Animal Health, Sandton, South Africa 5-7 weeks apart. Four of these females had been treated previously with the porcine zona pellucida (pZP vaccine for four years (2004-2007. Results All 12 monitored females (8 treated and 4 controls showed signs of luteal activity as evidenced by FPM concentrations exceeding individual baseline values more than once. A total of 16 oestrous cycles could be identified in 8 cows with four of these within the 13 to 17 weeks range previously reported for captive African elephants. According to the FPM concentrations the GnRH vaccine was unable to induce anoestrus in the treated cows. Overall FPM levels in samples collected during the wet season (mean 4.03 micrograms/gram dry faeces were significantly higher (P Conclusions The GnRH vaccination protocol failed to induce anoestrus in the treated female elephants. These results indicate that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity. The relationship between ecological conditions and endocrine activity were confirmed. Free-ranging female elephants were observed to not cycle continuously throughout the year in the absence of adult bulls.

  10. Gc-ms, hplc profiling, antioxidant, antimicrobial and cytotoxicity studies of malcolmia africana leaves

    International Nuclear Information System (INIS)

    Bokhari, T.H.; Rasool, N.; Riaz, M.; Riaz, M.

    2014-01-01

    Plants are known to be the richest source of natural antioxidant and antimicrobial properties. The use of herbs and medicinal plants as the first medicines is a universal phenomenon. The present study was carried out to examine the antioxidant, antimicrobial and cytotoxicity potential Malcolmia africana leaves extract, fraction, essential oil and fixed oil. The whole plant was extracted with absolute methanol and further fractionated with increasing polarity based absolute solvents. Different fractions were taken by solvent extraction method and their antimicrobial activities were determined. The IC50 and % inhibition by linoleic acid oxidation was evaluated for the antioxidant studies. The cytotoxicity of the plant extract and fractions were assayed against human blood erythrocytes (RBCs). The DPPH scavenging and linoleic acid oxidation assays were carried out. Qualitative and quantitative analysis of secondary metabolites was also carried out. The presence of phenolics was also studied by HPLC. The GC-MS analysis of Malcolmia africana essential oil and fixed oil was also carried out. (author)

  11. Cinco dificultades para construir la historia de la filosofía africana

    OpenAIRE

    de Diego González, Antonio

    2013-01-01

    Desde la teoría postcolonial se han cuestionado los modelos de historia de las ideas impuestos por el africanismo y el orientalismo. Diferentes teóricos africanos –Bachir Diagne, Mundimbe, Wiredu o Kete Asante– han formulado diversas soluciones para superar las dificultades. Este trabajo explora las principales dificultades y las propuestas para elaborar una historia de la filosofía africana. The postcolonial theory was questioning the patterns of History of Ideas imposed by Orientalism an...

  12. Corrosion Inhibition of Aluminium by Treculia Africana Leaves Extract in Acid Medium

    OpenAIRE

    Ejikeme, P.M.; Umana, S.G.; Onukwuli, O.D.

    2012-01-01

    The inhibitive effect of Treculia Africana leaves extract (TALE) in the corrosion of aluminium in HCl solution was studied using weight loss and thermometric methods at 30-60 °C. The results showed that TALE acted as a corrosion inhibitor of aluminium in HCl. Inhibition efficiency increased with increase in TALE concentration, but decreased with increase in temperature. TALE interaction with the metal surface was found to obey Freundlich and El-Awady adsorption isotherms. The obtained heats o...

  13. Antidiarrheal activity of methanolic extract of the root bark of Cordia africana.

    Science.gov (United States)

    Asrie, Assefa Belay; Abdelwuhab, Mohammedbrhan; Shewamene, Zewdneh; Gelayee, Desalegn Asmelashe; Adinew, Getnet Mequanint; Birru, Eshetie Melese

    2016-01-01

    An ethnobotanical study in Agew-Awi and Amhara peoples in northwest Ethiopia reported that Cordia africana is used traditionally in the treatment of liver disease, amebiasis, stomachache, and diarrhea. The root and root bark are reported to be used in the treatment of diarrhea. Therefore, this study was intended to evaluate the antidiarrheal effect of C. africana against castor oil-induced diarrhea in mice. The antidiarrheal effect of the plant was tested on castor oil-induced diarrhea in mice (23-25 g) of either sex. Number of diarrheic defecations, intestinal length traveled by the charcoal meal, and weight of intestinal fluid were taken as important parameters to evaluate the antidiarrheal activity of the plant extract. In preliminary phytochemical screening tests, the methanolic extract of C. africana was found to contain phenols, flavonoids, terpenoids, and saponins. Reduction in the number of diarrheic drops was observed in groups of mice that received 200 mg/kg ( P <0.05) and 400 mg/kg ( P <0.01) of the extract compared to the negative controls. The percent inhibition of intestinal fluid accumulation was 26.83%, 46.34%, and 53.66% at the doses of 100, 200, and 400 mg/kg of the extract, respectively. Relative to the negative control group, the mean percent of intestinal length moved by the charcoal meal was decreased by 24.41%, 39.89%, and 51.66% in groups of mice given 100, 200, and 400 mg/kg of the plant extract, respectively. To iterate the finding, the root bark extract of C. africana was found to be effective in preventing castor oil-induced diarrhea and intestinal motility in a dose-dependent manner. This reveals that the plant material has promising antidiarrheal activity as it is claimed in traditional medical practice.

  14. Antidiarrheal activity of methanolic extract of the root bark of Cordia africana

    OpenAIRE

    Asrie, Assefa Belay; Abdelwuhab, Mohammedbrhan; Shewamene, Zewdneh; Gelayee, Desalegn Asmelashe; Adinew, Getnet Mequanint; Birru, Eshetie Melese

    2016-01-01

    Assefa Belay Asrie, Mohammedbrhan Abdelwuhab, Zewdneh Shewamene, Desalegn Asmelashe Gelayee, Getnet Mequanint Adinew, Eshetie Melese Birru Department of Pharmacology, College of Medicine and Health Sciences, University of Gondar, Gondar, Ethiopia Abstract: An ethnobotanical study in Agew-Awi and Amhara peoples in northwest Ethiopia reported that Cordia africana is used traditionally in the treatment of liver disease, amebiasis, stomachache...

  15. Analgesic and anti-inflammatory effects of the methanol stem bark extract of Prosopis africana.

    Science.gov (United States)

    Ayanwuyi, Lydia O; Yaro, Abdullahi H; Abodunde, Olajumoke M

    2010-03-01

    Prosopis africana (Guill. & Perr.) Taub. (Mimosoideae) is a shrub used for menstrual and general body pain in Nupe land in north central Nigeria. In this study, the methanol extract of the stem bark of Prosopis africana (at doses of 62.5, 125, and 250 mg/kg) was evaluated for analgesic and anti-inflammatory activities using acetic acid-induced writhing assay and carrageenan-induced inflammation in rats. The extract significantly (P acetic acid-induced writhing with the highest activity observed at the highest dose, 250 mg/kg (76.89%) comparable to that of piroxicam (83.16%) the standard agent used. In the carrageenan-induced inflammation assay, the extract showed significant anti-inflammatory activity (P screening revealed the presence of flavonoids, saponins, carbohydrates, cardiac glycosides, tannins, and alkaloids. The oral median lethal dose was found to be 3807.9 mg/kg in mice and > 5000 mg/kg in rats. This study supports the folkloric claim of the use of Prosopis africana in the management of pain.

  16. New Sulphated Flavonoids from Tamarix africana and Biological Activities of Its Polar Extract.

    Science.gov (United States)

    Karker, Manel; De Tommasi, Nunziatina; Smaoui, Abderrazak; Abdelly, Chedly; Ksouri, Riadh; Braca, Alessandra

    2016-10-01

    The phytochemical investigation of Tamarix africana Poir. (Tamaricaceae) shoot polar extract afforded three new sulphated flavonoids, (2 S ,4 R )-5,7,4'-trihydroxyflavan-4-ol 5,7-disulphate ( 1 ), (2 S )-5,7,4'-trihydroxyflavan 7- O -sulphate ( 2 ), and (2 S )-naringenin 4'- O -sulphate ( 3 ), together with ten known compounds. Their structures were determined by spectroscopic methods including 1D and 2D NMR analysis and HRMS. Biological activities of the polar extract of T. africana shoots related to its phenolic content were also investigated. A high total phenolic content (151.1 mg GAE/g) was found in the methanol shoot extract, which exhibits strong antioxidant activities using the oxygen radical absorbance capacity method and a skin cell-based assay. Moreover, the shoot extract showed significant anti-inflammatory activity, reducing nitric oxide release by 53.5 % at 160 µg/mL in lipopolysaccharide-stimulated RAW 264.7 macrophages. Finally, T. africana shoot extract inhibited the growth of A-549 lung carcinoma cells, with an IC 50 value of 34 µg/mL. Georg Thieme Verlag KG Stuttgart · New York.

  17. El conflicto de Darfur: un reto para la credibilidad de la Unión Africana

    Directory of Open Access Journals (Sweden)

    María Ángeles Alaminos

    2008-01-01

    Full Text Available En el caso de la crisis de Darfur la Unión Africana esperaba conseguir su primer éxito a nivel internacional en la pacificación de un conflicto africano; el conflicto de Darfur ha supuesto un reto para su credibilidad. La Misión de la Unión Africana en Sudán (AMIS intentó poner fin a la crisis, pero los recursos limitados, tanto económicos como humanos fueron incapaces de frenarla. La protección de tres millones y medio de personas en situación de riesgo en Darfur ha constituido un desafío para la UA y una prueba de la efectividad de su misión AMIS. La Unión Africana quiere demostrar su valía como organización, su potencial en el desarrollo de acciones concretas, su preponderancia como actor en el ámbito africano y su relevancia como actor internacional.

  18. Biodiesel from the seed oil of Treculia africana with high free fatty acid content

    Energy Technology Data Exchange (ETDEWEB)

    Adewuyi, Adewale [Redeemer' s University, Department of Chemical Sciences, Faculty of Natural Sciences, Redemption City, Ogun State (Nigeria); Oderinde, Rotimi A.; Ojo, David F.K. [University of Ibadan, Industrial Unit, Department of Chemistry, Ibadan, Oyo State (Nigeria)

    2012-12-15

    Oil was extracted from the seed of Treculia africana using hexane. The oil was characterized and used in the production of biodiesel. Biodiesel was produced from the seed oil of T. africana using a two-step reaction system. The first step was a pretreatment which involved the use of 2 % sulfuric acid in methanol, and secondly, transesterification reaction using KOH as catalyst. Saponification value of the oil was 201.70 {+-} 0.20 mg KOH/g, free fatty acid was 8.20 {+-} 0.50 %, while iodine value was 118.20 {+-} 0.50 g iodine/100 g. The most dominant fatty acid was C18:2 (44 %). The result of the method applied showed a conversion which has ester content above 98 %, flash point of 131 {+-} 1.30 C, and phosphorus content below 1 ppm in the biodiesel. The biodiesel produced exhibited properties that were in agreement with the European standard (EN 14214). This study showed that the high free fatty acid content of T. africana seed oil can be reduced in a one-step pretreatment of esterification reaction using H{sub 2}SO{sub 4} as catalyst. (orig.)

  19. In Vivo Hypoglycemic Effect of Kigelia africana (Lam): Studies With Alloxan-Induced Diabetic Mice.

    Science.gov (United States)

    Njogu, Stephen M; Arika, Wycliffe M; Machocho, Alex K; Ngeranwa, Joseph J N; Njagi, Eliud N M

    2018-01-01

    The claims by the traditional herbal medicine practitioners that Kigelia africana has bioactivity against several diseases, including diabetes mellitus, were investigated in this study. Type I diabetes mellitus was induced in mice by intraperitoneal administration of alloxan monohydrate followed by treatment with the therapeutic doses of the aqueous and ethyl acetate leaf extract of K africana to the experimentally diabetic mice. The treatment effects were compared with the normal control, diabetic control, and diabetic control rats treated with a standard antidiabetic drugs (insulin administered intraperitoneally at 1 IU/kg body weight in 0.1 mL physiological saline or glibenclamide administered orally at 3 mg/kg body weight in 0.1 mL physiological saline). Phytochemical composition of the leaf extract was assessed using standard procedures and mineral elements assessed using atomic absorption spectrophotometry and total reflection X-ray fluorescence system. Oral and intraperitoneal administration of the aqueous and ethyl acetate leaf extract caused a statistically significant dose-independent reduction in plasma glucose level in alloxan-induced diabetic mice. The observed hypoglycemic activity of this plant extract could be attributed to the observed phytochemicals and trace elements, which have been associated with exhibiting antidiabetic properties. Therefore, the data appear to support the hypoglycemic effects of K africana validating its folkloric usage.

  20. Synergistic effect of sodium and yeast in improving the efficiency of DSSC sensitized with extract from petals of Kigelia Africana

    Science.gov (United States)

    Shalini, S.; Balasundaraprabhu, R.; Satish Kumar, T.; Sivakumaran, K.; Kannan, M. D.

    2018-05-01

    TiO2 nanostructures with two different dopants, sodium and yeast have been successfully synthesized by hydrothermal method. Doping sodium is found to extend the absorbance of TiO2 into the visible region as well as it acts as mordant in fixing and improving the absorption of dye. Yeast, as a dopant, can help in absorption of more anthocyanins from the natural dye extract by TiO2 and also aids in retaining the colour of the dye and increases the stability of the dye at varying pH. Anthocyanins are the major class of pigment present in the newly addressed maroon, velvety and trumpet shaped flower "Kigelia Africana". X-ray diffraction analysis revealed the formation of rutile phase for all the samples. Field Emission Scanning Electron microscopy images revealed the formation of nanorods and nanoflowers with change in dopant as well as their concentration. The photoelectric conversion efficiency of DSSC with undoped TiO2 photoelectrode is 0.87% and DSSC with 6% Na doped TiO2 photoelectrode is 1.56%. The efficiency of DSSC with 6% Na+6% yeast doped TiO2 photoelectrode is found to increase from 2.09% (DSSC with 6% Na+4% yeast doped TiO2 photoelectrode) to 2.31% on varying the dopant concentration. Doping is also found to increase the dye absorption and superior charge transport efficiency which in turn helps to improve the performance of DSSC.

  1. Evolutionary and demographic processes shaping geographic patterns of genetic diversity in a keystone species, the African forest elephant (Loxodonta cyclotis).

    Science.gov (United States)

    Ishida, Yasuko; Gugala, Natalie A; Georgiadis, Nicholas J; Roca, Alfred L

    2018-05-01

    The past processes that have shaped geographic patterns of genetic diversity may be difficult to infer from current patterns. However, in species with sex differences in dispersal, differing phylogeographic patterns between mitochondrial (mt) and nuclear (nu) DNA may provide contrasting insights into past events. Forest elephants ( Loxodonta cyclotis ) were impacted by climate and habitat change during the Pleistocene, which likely shaped phylogeographic patterns in mitochondrial (mt) DNA that have persisted due to limited female dispersal. By contrast, the nuclear (nu) DNA phylogeography of forest elephants in Central Africa has not been determined. We therefore examined the population structure of Central African forest elephants by genotyping 94 individuals from six localities at 21 microsatellite loci. Between forest elephants in western and eastern Congolian forests, there was only modest genetic differentiation, a pattern highly discordant with that of mtDNA. Nuclear genetic patterns are consistent with isolation by distance. Alternatively, male-mediated gene flow may have reduced the previous regional differentiation in Central Africa suggested by mtDNA patterns, which likely reflect forest fragmentation during the Pleistocene. In species like elephants, male-mediated gene flow erases the nuclear genetic signatures of past climate and habitat changes, but these continue to persist as patterns in mtDNA because females do not disperse. Conservation implications of these results are discussed.

  2. Comparative study of physicochemical analysis of prosopis africana seeds fermented with different starter cultures

    Directory of Open Access Journals (Sweden)

    G. P. Oyeyiola

    2017-01-01

    Full Text Available Prosopis africana (African mesquite is one of the lesser known legume seed crops in Nigeria, which in a fermented state, gives a food condiment. Because of its rich protein content (about 34%, efforts are made to utilize some lesser known legumes to improve the nutritional status of the people. This study was carried out by fermenting Prosopis africana seeds with mono and mixed cultures of bacterial isolates to produce a local condiment called Okpehe. Standard AOAC methods were used to determine the pH, total sugar and crude protein content of the fermented seeds. During the production of Okpehe with mono cultures of bacteria, the pH ranged between 6.80 and 8.92; total sugar between 10.2 and 7.5 mg/g, and crude protein between 34.62 and 41.25%. In the mixed culture inoculated samples, the pH increased from 7.00 to 8.92; total sugar decreased from 9.4 to 7.4 mg/g, while the crude protein increased (35.02 - 44.61% significantly (p < 0.05 as the fermentation progressed. The highest crude protein content of 44.61% was obtained with the combination of Bacillus subtilis and Bacillus licheniformis, while the lowest protein content referred to the combination of Bacillus megaterium and Bacillus pumilus. The result of this study showed that Prosopis africana seeds could be utilized for the production of Okpehe using mixed cultures of B. subtilis and B. licheniformis, so as to increase the protein intake of the populace.

  3. Antibacterial, antifungal and antioxidant activity of Olea africana against pathogenic yeast and nosocomial pathogens.

    Science.gov (United States)

    Masoko, Peter; Makgapeetja, David M

    2015-11-17

    Olea africana leaves are used by Bapedi people to treat different ailments. The use of these leaves is not validated, therefore the aim of this study is to validate antimicrobial properties of this plant. The ground leaves were extracted using solvents of varying polarity (hexane, chloroform, dichloromethane (DCM), ethyl acetate, acetone, ethanol, methanol, butanol and water). Thin layer chromatography (TLC) was used to analyse the chemical constituents of the extracts. The TLC plates were developed in three different solvent systems, namely, benzene/ethanol/ammonium solution (BEA), chloroform/ethyl acetate/formic acid (CEF) and ethyl acetate/methanol/water (EMW). The micro-dilution assay and bioautography method were used to evaluate the antibacterial activity of the extracts against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus and the antifungal activity against Candida albicans and Cryptococcus neoformans. Methanol was the best extractant, yielding a larger amount of plant material whereas hexane yielded the least amount. In phytochemical analyses, more compounds were observed in BEA, followed by EMW and CEF. Qualitative 2, 2- diphenylpacryl-1-hydrazyl (DPPH) assay displayed that all the extracts had antioxidant activity. Antioxidant compounds could not be separated using BEA solvent system while with CEF and EMW enabled antioxidant compounds separation. The minimum inhibitory concentrations (MIC) values against test bacteria ranged between 0.16 and 2.50 mg/mL whereas against fungi, MIC ranged from 0.16 to 0.63 mg/mL. Bioautography results demonstrated that more than one compound was responsible for antimicrobial activity in the microdilution assay as the compounds were located at different Rf values. The results indicate that leaf extracts of Olea africana contain compounds with antioxidant, antibacterial and antifungal activities. Therefore, further studies are required to isolate the active compounds and perform

  4. Potentials of leaves of Aspilia africana (Compositae in wound care: an experimental evaluation

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    Akah PA

    2007-07-01

    Full Text Available Abstract Background The potentials of the leaves of the haemorrhage plant, Aspilia africana C. D Adams (Compositae in wound care was evaluated using experimental models. A. africana, which is widespread in Africa, is used in traditional medicine to stop bleeding from wounds, clean the surfaces of sores, in the treatment of rheumatic pains, bee and scorpion stings and for removal of opacities and foreign bodies from the eyes. The present study was undertaken to evaluate the potentials for use of leaves of this plant in wound care. Methods The effect of the methanol extract (ME and the hexane (HF and methanol (MF fractions (obtained by cold maceration and graded solvent extraction respectively on bleeding/clotting time of fresh experimentally-induced wounds in rats, coagulation time of whole rat blood, growth of microbial wound contaminants and rate of healing of experimentally-induced wounds in rats were studied as well as the acute toxicity and lethality (LD50 of the methanol extract and phytochemical analysis of the extract and fractions. Results The extract and fractions significantly (P ME>HF. Also, the extract and fractions caused varying degrees of inhibition of the growth of clinical isolates of Pseudomonas fluorescens and Staphylococcus aureus, as well as typed strains of Ps. aeruginosa (ATCC 10145 and Staph. aureus (ATCC 12600, and reduced epithelialisation period of wounds experimentally-induced in rats. Acute toxicity and lethality (LD50 test in mice established an i.p LD50 of 894 mg/kg for the methanol extract (ME. Phytochemical analysis revealed the presence of alkaloids, saponins, tannins, flavonoids, resins, sterols, terpenoids and carbohydrates. Conclusion The leaves of A. africana possess constituents capable of arresting wound bleeding, inhibiting the growth of microbial wound contaminants and accelerating wound healing which suggest good potentials for use in wound care.

  5. Cephaloleia sp. Cerca a Vagelineata Pic*, una Plaga de la Palma Africana

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    Urueta Sandino Eduardo

    1972-08-01

    Full Text Available Cephalolia sp. y Cephaloleila sp, se han empleado como sinónimos del género Cepaloleia sp. (Lepesme. 1947. Se sabe que los estados de larva y adulto atacan el follaje de la palma africana (Elaeis guineensis Jacq. trayendo muchas veces como consecuencia secamientos en los folíolos o su invasión por hongos. En Colombia el Cephaloleia próximo a vagelineata Pic se presenta en la zona de Urabá y posiblemente en el Departamento de Santander.

  6. Liberation Through Education: Teaching #BlackLivesMatter in Africana Studies

    OpenAIRE

    Danielle M. Wallace

    2016-01-01

    This paper is based on teaching about #BlackLivesMatter in Africana Studies in two seminar courses during the Spring of 2015 and 2016, respectively. Guided by a pedagogy grounded in the belief that education can be a tool of social justice, arguments are made for how to frame discussions of #BlackLivesMatter in regard to the socio-historical circumstances that inform and shape the modern day movement. In addition, suggestions are made for including a discussion of the tradition of activism wi...

  7. EVALUATION OF CEMENT-BONDED PARTICLE BOARD PRODUCED FROM AFZELIA AFRICANA WOOD RESIDUES

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    OLUFEMI A. SOTANNDE

    2012-12-01

    Full Text Available The study was design to evaluate the physical and mechanical properties of cement-bonded particleboards produced from Afzelia africana wood residues. The production variables investigated were three wood particle types (flakes, flake-sawdust mix and sawdust, three chemical accelerators (CaCl2, MgCl2 and AlCl3 and four wood-cement ratios (1:2.0, 1:2.5, 1:3.0 and 1:3.5. The accelerators were based on 2% by weight of cement used. The boards produced were subjected to physical tests such as density, percentage water absorption and thickness swelling. Mechanical properties evaluated were modulus of rupture, internal bonding strength and compressive strength. The results revealed that the type of particle used, wood-cement ratio and chemical additives had a marked influence on the physical and mechanical properties of the boards (p < 0.05. From quality view point, flake-sawdust composite ranked best while flake boards ranked least. Similarly, CaCl2 had the best influence on the setting of the boards followed by MgCl2 and AlCl3. Finally, it has been shown that particle boards that satisfied the BISON type HZ requirement and ISO 8335 can be produced from Afzelia africana particularly at wood-cement of 1:2.5 and above.

  8. Comparative study of the chemical composition and mineral element content of Artocarpus heterophyllus and Treculia africana seeds and seed oils.

    Science.gov (United States)

    Ajayi, Ibironke Adetolu

    2008-07-01

    A comparative study of Artocarpus heterophyllus and Treculia africana seeds, both of Moraceae family, was carried out to establish their chemical compositions and evaluate their mineral element content in order to investigate the possibility of using them for human and or animal consumption and also to examine if there is a relationship between the properties of these seeds. A. heterophyllus and T. africana are rich in protein; their protein contents are higher than those from high protein animal sources such as beef and marine fishes. Both seeds have high carbohydrate content and could act as source of energy for animals if included in their diets. The oil contents of the seeds are 11.39% and 18.54% for A. heterophyllus and T. africana, respectively. The oils are consistently liquid at room temperature. The results of the physicochemical properties of the two seeds are comparable to those of conventional oil seeds such as groundnut and palm kernel oils and could be useful for nutritional and industrial purposes. The seeds were found to be good sources of mineral elements. The result revealed potassium to be the prevalent mineral elements which are 2470.00 ppm and 1680.00 ppm for A. heterophyllus and T. africana, respectively followed by sodium, magnesium and then calcium. They also contain reasonable quantity of iron, in particular A. heterophyllus 148.50 ppm.

  9. The effects of smoke derivatives on in vitro seed germination and development of the leopard orchid Ansellia africana

    Czech Academy of Sciences Publication Activity Database

    Papenfus, H. B.; Naidoo, D.; Pošta, Martin; Finnie, J. F.; van Staden, J.

    2016-01-01

    Roč. 18, č. 2 (2016), s. 289-294 ISSN 1435-8603 Institutional support: RVO:61388963 Keywords : Ansellia africana * developmental rate index * germination rate index * karrikinolide * leopard orchid * smoke-water * trimethylbutenolide Subject RIV: CC - Organic Chemistry Impact factor: 2.106, year: 2016

  10. Use patterns, use values and management of Afzelia africana Sm. in Burkina Faso: implications for species domestication and sustainable conservation.

    Science.gov (United States)

    Balima, Larba Hubert; Nacoulma, Blandine Marie Ivette; Ekué, Marius Rodrigue Mensah; Kouamé, François N'Guessan; Thiombiano, Adjima

    2018-03-27

    The lack of literature on the interactions between indigenous people and the valuable agroforestry trees hinder the promotion of sustainable management of plant resources in West African Sahel. This study aimed at assessing local uses and management of Afzelia africana Sm. in Burkina Faso, as a prerequisite to address issues of domestication and sustainable conservation. One thousand forty-four peoples of seven dominant ethnic groups were questioned in 11 villages through 221 semi-structured focus group interviews. The surveys encompassed several rural communities living around six protected areas along the species distribution range. Questions refer mainly to vernacular names of A. africana, locals' motivations to conserve the species, the uses, management practices and local ecological knowledge on the species. Citation frequency was calculated for each response item of each questionnaire section to obtain quantitative data. The quantitative data were then submitted to comparison tests and multivariate statistics in R program. A. africana is a locally well-known tree described as a refuge of invisible spirits. Due to this mystery and its multipurpose uses, A. africana is conserved within the agroforestry systems. The species is widely and mostly used as fodder (87.55%), drugs (75.93%), fetish or sanctuary (70.95%), food (41.49%), and raw material for carpentry (36.19%) and construction (7.05%). While the uses as fodder, food and construction involved one organ, the leaves and wood respectively, the medicinal use was the most diversified. All tree organs were traditionally used in 10 medical prescriptions to cure about 20 diseases. The species use values differed between ethnic groups with lower values within the Dagara and Fulani. The findings reveal a total absence of specific management practices such as assisted natural regeneration, seeding, or transplantation of A. africana sapling. However, trees were permanently pruned and debarked by local people

  11. BEHAVIOR OF CÓRDIA AFRICANA (Cordia africana Lam. CULTIVATED IN SOIL CONTAMINATED BY HEAVY METALS AND TREATED WITH AMENDMENT MATERIALS

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    Ana Carolina Callegario Pereira

    2013-08-01

    Full Text Available http://dx.doi.org/10.5902/1980509810544This study aimed to evaluate the remediation of two soils contaminated with heavy metals from soil excavations, located near the port of Itaguaí, through the techniques of chemical immobilization and phytostabilization using the species Cordia africana. The data were collected in the ore courtyard from ‘Companhia Siderúgica Nacional’ (CSN, in the port of Itaguaí, Rio de Janeiro state. In order to reduce the solubility of heavy metals present in these substrates, two industrial waste products produced by CSN were used as ameliorating products, the steelmaking slag and the mill scale, in different concentrations. The plant species was considered with potential to be used in programs of phytostabilization, due to its heavy metal tolerance studied and to high accumulation of such elements in roots and stem. In the substrate of low combination, the lowest accumulation of Zinc and Cadmium in stems and leaves occurred with the use of 4% of soothing. In the substrate of high accumaltion it was 6%.

  12. Differentiation in a geographical mosaic of plants coevolving with ants: phylogeny of the Leonardoxa africana complex (Fabaceae: Caesalpinioideae) using amplified fragment length polymorphism markers.

    Science.gov (United States)

    Brouat, C; McKey, D; Douzery, E J P

    2004-05-01

    Comprising four allopatric subspecies that exhibit various grades of ant-plant interactions, from diffuse to obligate and symbiotic associations, the Leonardoxa africana complex (Fabaceae, Caesalpinioideae) provides a good opportunity to investigate the evolutionary history of ant-plant mutualisms. A previous study of the L. africana complex based on chloroplast DNA noncoding sequences revealed a lack of congruence between clades suggested by morphological and plastid characters. In this study, we analysed phylogenetic relationships within the L. africana complex using a Bayesian probability approach on amplified fragment length polymorphism markers. The results reported permit partial validation of the four subspecies of L. africana previously defined by morphological and ecological markers. Incongruences between phylogenies based on chloroplast DNA and amplified fragment length polymorphism markers are discussed in the light of morphological and ecological data, and confronted with hypotheses of convergence, lineage sorting and introgression.

  13. ANALGESIC ACTIVITY OF PET ETHER, AQUEOUS, AND HYDRO-ETHANOLIC LEAF EXTRACTS OF ASPILIA AFRICANA (PERS) C.D. ADAMS (ASTERACEAE) IN RODENTS

    OpenAIRE

    Koffuor George Asumeng; Ameyaw Elvis Ofori; Oppong Kyekyeku James; Amponsah Kingsley Isaac; Sunkwa Andrews; Semenyo Samuella Afriyie

    2013-01-01

    Traditionally, Aspilia africana is used in the management of pain in Ghana and most parts of West Africa. This study therefore investigated the analgesic effect of the petroleum ether, aqueous, and hydro-ethanolic leaf extracts of Aspilia africana using rodent models. Preliminary phytochemical screening was done on all the extracts, which showed the presence of alkaloids, flavonoids, saponins, tannins, glycosides, phytosterols and terpenoids. The extracts (40-400 mg/kg p.o.) were administered...

  14. Vegetative Propagation Trial of Prosopis africana (Guill. et Perr.) Taub. by Air Layering under Sudano-Sahelian Climate in the South-Central Niger

    OpenAIRE

    Abdou, Laouali; Karim, Saley; Habou, Rabiou; Mahamane, Ali

    2015-01-01

    Prosopis africana is a species of great socioeconomic importance but threatened with extinction in Niger because of overuse and regeneration problem. This study, conducted in the Maradi (Niger) area, precisely at El Gueza in the south of Gazaoua department, aims to evaluate the vegetative propagation capacity of P. africana by air layering under the Sudano-Sahelian climate of the south-central Niger. A ring of bark was taken on each selected branch and the wound was covered with a black plast...

  15. Antioxidant activity of ethanolic extract of inflorescence of Ormenis Africana in vitro and in cell cultures

    Science.gov (United States)

    2011-01-01

    Background The antioxidant potency of the hydroethanolic extract of Ormenis Africana (HEOA), Asteraceae was evaluated with regards to total polyphenol, flavonoid and anthocyanins content. Antioxidant activity has been assessed chemically and biologically. First, the free radical scavenging ability of HEOA was evaluated using two commonly in vitro tests: ABTS and DPPH radicals. Then, the protection effect of this extract against oxidative stress was conducted in HeLa cells treated with Fe2+ or H2O2. Oxidative stress was evaluated by measuring the lipid peroxidation levels (TBARs and DC) and the antioxidant enzymes activities (catalase and Superoxide dismutase). Cytotoxic effect of HEOA was prealably determined against HeLa cell line by MTT assay. Results HEOA contain considerable levels of antioxidant compound as evidenced by high amount of polyphenols (312.07 mg GAE/g dray matter), flavonoids (73.72 ± 1.98 mg QE/g dray matterl) and anthocyanins (0.28 ± 0.09 mg Cy-3-glu E/g dray matter). DPPH and ABTS assays showed a high antioxidant activity (IC50 = 24 μg/ml; TEAC = 2.137 mM) which was comparable to BHT. In biological system, HEOA exhibited a 50% cytotoxic concentration evaluated as 16.52 μg/ml. Incubation of HeLa cell line with no cytotoxic concentrations resulted in a remarkable protection from oxidative stress induced by Fe2+ or H2O2 which was evidenced by a decrease of MDA and CD levels as well as a diminution of antioxidant enzymes activities (Catalase and SOD) as compared to cells treated with Fe2+ or H2O2 alone. Conclusion The hydroethanolic extract of O. Africana could thus be considered as a source of potential antioxidants. The results of this study will promote the reasonable usage of this plant in food and pharmacy industries as well as in alternative medicine and natural therapy. PMID:21575256

  16. Secondary Metabolites from Jacaranda Mimosifolia and Kigelia Africana (Bignoniaceae and Their Anticandidal Activity

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    Lazare Sidjui Sidjui

    2014-05-01

    Full Text Available From the stem barks of Jacaranda mimosifolia benzoic acid (1, 1-naphthaleneacetic acid, 5-carboxy- 1,2,3,4,4a,7,8,8a-octahydro-1,2,4a-trimethyl-[1S-(1α,2β,4aβ,8aα] ( 2, betulinic acid ( 3, lupeol (4 and ursolic acid (5 were isolated. Similarly, lapachol (6, dehydro-α-lapachone (7, 2- acetylfuro-1, 4-naphthoquinone (8, p-coumaric acid (9, caffeic acid (10, nonacosanoic acid, 2-(4-hydroxyphenylethyl ester (11, β-sitosterol (12, kigelinol (13, oleanolic acid (14, β-friedelinol (15, pomolic acid (16, and kojic acid (17 were isolated from the stem barks of Kigelia africana. All the isolated compounds were characterized by using spectroscopic methods especially 1D and 2D NMR and ESI mass spectrometry and comparison with literature data. To the best of our knowledge, compounds 1, 2, 3 and 5, and compounds 11, 14, 15 and 16 were isolated for the first time from Jacaranda mimosifolia and Kigelia africana, respectively. All these compounds were screened for anticandidal activity by agar diffusion method and microbroth dilution technique on four Candida albicans strains (ATCCL26, ATCC12C, ATCCP37039, and ATCCP37037. Among them, compounds 9, 10, and 17 exhibited the highest anticandidal activity that varied between the microbial species (MIC= 0.01 ± 0.00 − 0.03 ± 0.00 mg/mL on C. albicans ATCCL26, ATCCP37037, ATCCP37039 and ATCC12C strains. Compound 17 was likely the most active against the four Candida albicans strains (MIC= 0.01 ± 0.00 − 0.02 ± 0.00 mg/mL.

  17. Improvement of growth, fermentative efficiency and ethanol tolerance of Kloeckera africana during the fermentation of Agave tequilana juice by addition of yeast extract.

    Science.gov (United States)

    Díaz-Montaño, Dulce M; Favela-Torres, Ernesto; Córdova, Jesus

    2010-01-30

    The aim of this work was to improve the productivity and yield of tequila fermentation and to propose the use of a recently isolated non-Saccharomyces yeast in order to obtain a greater diversity of flavour and aroma of the beverage. For that, the effects of the addition of different nitrogen (N) sources to Agave tequilana juice on the growth, fermentative capacity and ethanol tolerance of Kloeckera africana and Saccharomyces cerevisiae were studied and compared. Kloeckera africana K1 and S. cerevisiae S1 were cultured in A. tequilana juice supplemented with ammonium sulfate, diammonium phosphate or yeast extract. Kloeckera africana did not assimilate inorganic N sources, while S. cerevisiae utilised any N source. Yeast extract stimulated the growth, fermentative capacity and alcohol tolerance of K. africana, giving kinetic parameter values similar to those calculated for S. cerevisiae. This study revealed the importance of supplementing A. tequilana juice with a convenient N source to achieve fast and complete conversion of sugars in ethanol, particularly in the case of K. africana. This yeast exhibited similar growth and fermentative capacity to S. cerevisiae. The utilisation of K. africana in the tequila industry is promising because of its variety of synthesised aromatic compounds, which would enrich the attributes of this beverage. (c) 2009 Society of Chemical Industry.

  18. Evaluation of the effects of Olea europaea L. subsp. africana (Mill.) P.S. Green (Oleaceae) leaf methanol extract against castor oil-induced diarrhoea in mice.

    Science.gov (United States)

    Amabeoku, George J; Bamuamba, Kapinga

    2010-03-01

    Olea europaea L. subsp. africana (Mill.) P.S. Green is widely used in South Africa by traditional medicine practitioners to treat diarrhoea. However, little is known scientifically about this South African species in the treatment of diarrhoea. The main aim of the study therefore was to investigate the antidiarrhoeal effect of the leaf methanol extract of the plant species in mice. The antidiarrhoeal activity of the leaf methanol extract of O. europaea subsp. africana was studied using a castor oil-induced diarrhoeal test. The antipropulsive activity of the plant extract was also investigated using the charcoal meal transit test. Standard methods were used to investigate the acute toxicity and effect of O. europaea subsp. africana on castor oil-induced intraluminal fluid accumulation. Leaf methanol extract of O. europaea subsp. africana and loperamide, a standard antidiarrhoeal drug, significantly reduced the number of diarrhoeal episodes induced by castor oil, significantly decreased the stool mass, significantly delayed the onset of the diarrhoea and protected the animals against castor oil-induced diarrhoea. Both O. europaea subsp. africana and loperamide significantly decreased the gastrointestinal transit of charcoal meal and castor oil-induced intraluminal fluid accumulation in mice. The LD50 value was found to be 3475 mg/kg (p.o.). The results obtained suggest that the leaf methanol extract of O. europaea subsp. africana has an antidiarrhoeal property and that, given orally, it may be non-toxic and/or safe in mice.

  19. Una valoración de la geografía y la diáspora africana

    Directory of Open Access Journals (Sweden)

    Judith A. Carney

    2006-01-01

    Full Text Available El estudio de la diáspora Africana se ha vuelto un area vibrante de investigación y enseñanza en los años recientes a través de las disciplinas. Sin embargo, hay muy pocas contribuciones geográficas. Este artículo busca invertir esta tendencia. Se revisa el trabajo relevante de geógrafos en el Atlántico Negro para identificar temas prometedores para la investigación futura. La dispersión de plantas Africanas y el papel de los esclavos en establecer estas plantas es especialmente prometedor. Esta dirección de investigación clarifica los componentes Africanos de Intercambio Colombino mientras llama la atención sobre la importancia de la subsistencia en el negocio transatlántico de esclavos y la economía de las plantaciones. Las comidas básicas de origen Africano sirvieron a la subsistencia y a la memoria. Plantas Africanas figuran de manera prominente en los caminos de la comida en la diáspora, las practicas litúrgicas de las religiones Afro-sincréticas, y en las historias orales de Maroon.

  20. Prunus africana (Hook.f.) Kalkman: the overexploitation of a medicinal plant species and its legal context.

    Science.gov (United States)

    Bodeker, Gerard; van 't Klooster, Charlotte; Weisbord, Emma

    2014-11-01

    The linkage between herbal medicines and the sustainability of medical plants from which they are manufactured is increasingly being understood and receiving attention through international accords and trade labeling systems. However, little attention is paid to the fair trade aspects of this sector, including the issue of benefit-sharing agreements with traditional societies whose knowledge and resources are being exploited for commercial herbal medicine development and production. This article examines the case of Prunus africana (Hook.f.) Kalkman, from equatorial Africa. While the conservation and cultivation dimension of the trade in P. africana has been much discussed in literature, no research appears to have focused on the traditional resource rights and related ethical dimensions of this trade in traditional medicine of Africa. Serving as a cautionary tale for the unbridled exploitation of medicinal plants, the history of P. africana extraction is considered here in the context of relevant treaties and agreements existing today. These include the Nagoya Protocol, a supplementary agreement to the Convention on Biological Diversity, the Trade-Related Aspects of Intellectual Property Rights agreement from the World Trade Organization, and two African regional frameworks: the Swakopmund Protocol and the Organisation Africaine de la Propriété Intellectuelle Initiative. In the context of strengthening medicinal plant research in Africa, a novel international capacity-building project on traditional medicines for better public health in Africa will be discussed, illustrating how access and benefit sharing principles might be incorporated in future projects on traditional medicines.

  1. Isolation of a Novel Fusogenic Orthoreovirus from Eucampsipoda africana Bat Flies in South Africa

    Directory of Open Access Journals (Sweden)

    Petrus Jansen van Vuren

    2016-02-01

    Full Text Available We report on the isolation of a novel fusogenic orthoreovirus from bat flies (Eucampsipoda africana associated with Egyptian fruit bats (Rousettus aegyptiacus collected in South Africa. Complete sequences of the ten dsRNA genome segments of the virus, tentatively named Mahlapitsi virus (MAHLV, were determined. Phylogenetic analysis places this virus into a distinct clade with Baboon orthoreovirus, Bush viper reovirus and the bat-associated Broome virus. All genome segments of MAHLV contain a 5' terminal sequence (5'-GGUCA that is unique to all currently described viruses of the genus. The smallest genome segment is bicistronic encoding for a 14 kDa protein similar to p14 membrane fusion protein of Bush viper reovirus and an 18 kDa protein similar to p16 non-structural protein of Baboon orthoreovirus. This is the first report on isolation of an orthoreovirus from an arthropod host associated with bats, and phylogenetic and sequence data suggests that MAHLV constitutes a new species within the Orthoreovirus genus.

  2. Evaluation of Antibacterial and Antioxidant Activity of Leaves, Fruit and Bark of Kigelia Africana

    International Nuclear Information System (INIS)

    Fatima, I.; Shabir, S.; Bano, S.

    2016-01-01

    In vitro antibacterial activity of extracts was tested against six bacterial strains viz. Staphylococcus aureus, Proteus vulgaris, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Citrobacter amalonaticus by agar-disc diffusion method. Ethanol and n-hexane were used as negative control and oxytetracycline was used as a positive control. Ethanolic and aqueous extracts of bark and leaves of Kigelia africana showed remarkable activity against various bacterial strains as compared to n-hexane. S. aureus and E. coli were proved as highly sensitive strains while K. pneumonia was the resistant strain as the extracts formed no inhibition zone against it. The percentage of antioxidant activity of different parts of Kigelia was assessed by DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical assay. Quercetin was used as a standard antioxidant which showed 93.6 percent inhibition. Kigelia bark extract showed good antioxidant activity i.e., 67.33 percent inhibition, fruit extract possess moderate antioxidant activity i.e., 62.66 percent inhibition while leaves showed the poor antioxidant activity i.e., 59.66 percent DPPH inhibition respectively. Overall, the comparative analysis revealed that bark extract exhibited the most remarkable antibacterial as well as antioxidant activity as compared to leaves and fruit extracts. (author)

  3. The hypolipidemic effects of Afzelia africana in type II diabetic patients in Nigeria.

    Science.gov (United States)

    Nwosu, M C; Odenigbo, U M; Odenigbo, U C

    2006-01-01

    The projected rise in the world prevalence of diabetes mellitus poses new challenges in poor countries. Soluble fibre incorporation into the diet of diabetic patients has been shown to reduce the glyceamia and lipaemia of diabetes mellitus. The hypolipidemic effect of soluble fibre supplementation using the seed of locally available legume tree plant--Afzelia africana was studied in 13 Nigerian patients with type 2 diabetes mellitus. The subjects were randomly selected from the out patient diabetes mellitus clinic of Nnamdi Azikiwe University Teaching Hospital, Nnewi. They were fed with unsupplemented and supplemented standardized diet for the first 2 days and subsequent 4 days respectively. The fibre supplementation was prepared and incorporated into the meal portions according to previously described technique and acceptability study. The fasting serum levels of TC, TG, HDL-C, LDL-C and HDL/TC ratio were estimated before and after the unsupplemented and fibre supplemented meals. The data obtained were analyzed using paired t-test. The correlation between the total energy requirement and the reduction in TC, pre and post fibre supplemented meals were determined using the linear coefficients. The results showed a significant reduction (P 0.05). The exploitation and incorporation of this source of soluble fibre in diabetic diets reduced the lipaemia of diabetes mellitus.

  4. Specialised use of working memory by Portia africana, a spider-eating salticid.

    Science.gov (United States)

    Cross, Fiona R; Jackson, Robert R

    2014-03-01

    Using expectancy-violation methods, we investigated the role of working memory in the predatory strategy of Portia africana, a salticid spider from Kenya that preys by preference on other spiders. One of this predator's tactics is to launch opportunistic leaping attacks on to other spiders in their webs. Focussing on this particular tactic, our experiments began with a test spider on a ramp facing a lure (dead prey spider mounted on a cork disc) that could be reached by leaping. After the test spider faced the lure for 30 s, we blocked the test spider's view of the lure by lowering an opaque shutter before the spider leapt. When the shutter was raised 90 s later, either the same lure came into view again (control) or a different lure came into view (experimental: different prey type in same orientation or same prey type in different orientation). We recorded attack frequency (number of test spiders that leapt at the lure) and attack latency (time elapsing between shutter being raised and spiders initiating a leap). Attack latencies in control trials were not significantly different from attack latencies in experimental trials, regardless of whether it was prey type or prey orientation that changed in the experimental trials. However, compared with test spiders in the no-change control trials, significantly fewer test spiders leapt when prey type changed. There was no significant effect on attack frequency when prey orientation changed. These findings suggest that this predator represents prey type independently of prey orientation.

  5. Prevalence of Candida albicans, Candida dubliniensis and Candida africana in pregnant women suffering from vulvovaginal candidiasis in Argentina.

    Science.gov (United States)

    Mucci, María Josefina; Cuestas, María Luján; Landanburu, María Fernanda; Mujica, María Teresa

    Vulvovaginal candidiasis (VVC) is a vulvovaginitis commonly diagnosed in gynecology care. In recent years, the taxonomy of the most important pathogenic Candida species, such as Candida albicans have undergone significant changes. This study examined the prevalence of C. albicans, Candida africana, and Candida dubliniensis in vaginal specimens from 210 pregnant women suffering from vulvovaginitis or having asymptomatic colonization. Phenotypic and molecular methods were used for the identification of the species. During the studied period, 55 isolates of Candida or other yeasts were obtained from specimens collected from 52 patients suffering from vulvovaginitis (24.8%). C. albicans was the predominant Candida species in 42 isolates (80.7%), either alone or in combination with other species of the genus (5.7%, n=3). Additionally, nine isolates of C. albicans (50%) were obtained from asymptomatic patients (n=18). C. dubliniensis was the causative agent in 2 (3.8%) cases of VVC, and was also isolated in one asymptomatic patient. Molecular assays were carried out using specific PCR to amplify the ACT1-associated intron sequence of C. dubliniensis. The amplification of the HWP1 gene also correctly identified isolates of the species C. albicans and C. dubliniensis. No C. africana was isolated in this work. Some C. albicans isolates were either homozygous or heterozygous at the HWP1 locus. The distribution of heterozygous and homozygous C. albicans isolates at the HWP1 locus was very similar among patients suffering from VVC and asymptomatic patients (p=0.897). The presence of C. albicans and C. dubliniensis, and the absence of C. africana in pregnant is noteworthy. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  6. Functional and anti-nutritional properties, in-vitro protein digestibility and amino acid composition of dehulled afzelia africana seeds

    International Nuclear Information System (INIS)

    Ogungbenle, H.N.; Omaejalile, M.

    2010-01-01

    Analysis of Afzelia africana seed flour showed that the seeds possessed high water absorption capacity (128.31%), good oil absorption capacity (588.49%) and fairly good emulsion property (35.25%). However, it had the Least gelation concentration (6 .00% w/v) and foaming properties ( 8.00%,3 .00%). Anti-nutritional factors were very low, with the highest being phytate (13.59/o) and tannin the least (0.43%). Total amino acid composition was 796.6 mg/g protein. Essentiaal amino acids (48.5%)w ere in high proportion with in-vitro digestibility of 71.5%. (author)

  7. Autoras africanas: A favor de las mujeres=African authors: In favor of women

    Directory of Open Access Journals (Sweden)

    Socorro Suárez Lafuente

    2017-06-01

    Full Text Available Resumen: La cultura occidental produce binomios de poder fuertemente inscritos en el lenguaje y el imaginario colectivo. Las subversiones aparecen primero en la zona dominante, como el feminismo, que se extiende, posteriormente, a otros feminismos, igualmente lógicos y reivindicativos, pero con menos capacidad de visibilización en un mundo globalizado. Las mujeres de grupos minorizados que han conseguido acceder a la educación han levantado sus voces y utilizado su potencial creativo a favor de las silenciadas de su cultura, a las que no alcanzaban el feminismo blanco occidental. Amma Darko, Bessie Head y Chimamanda Ngozi Adichie son algunos de los nombres que encabezan un movimiento africano feminista, que prioriza la libertad individual de las mujeres y les hace sentirse orgullosas de ser africanas.   Abstract Western culture produces binaries of power that are deeply inscribed both in language and in the collective imaginarium. Subversions tend to appear in the more affluent class, as is the case with feminism, which later extend to other feminisms, equally important and vindicatory, but with fewer opportunities to become visible within a globalized world. Many women from minoritized groups have had access to education, have been able to use their creative force and have become the voice of many silent women who were not included in the successive waves of Western feminisms. Amma Darko, Bessie Head and Chimamanda Ngozi Adichie are but a few names at the forefront of African feminism, a movement that fights for the individual rights of women and makes them feel proud of their Africanism.

  8. Hilos descoloniales. Trans-localizando los espacios de la diáspora africana

    Directory of Open Access Journals (Sweden)

    Agustín Lao-Montes

    2007-01-01

    Full Text Available Este artículo desarrolla un argumento teórico y metodológico sobre cómo analizar y transformar la modernidad capitalista a partir de una conceptualización de la diáspora africana como categoría geo-histórica clave que significa, por un lado un proceso de larga duración dentro del cual se constituyen sujetos históricos, expresiones culturales, corrientes intelectuales y movimientos sociales; por otro lado una condición moderna/colonial tanto de opresión (en todas sus dimensiones: culturales, socio-económicas, políticas, epistémicas y existenciales como de agencia histórica y auto-desarrollo de los sujetos de la Africanía moderna; y tercero como un proyecto descolonizador de liberación que se afirma y articula en el accionar de los sujetos, pueblos y movimientos afrodiaspóricos. Eel artículo esboza una genealogía de las diásporas afroamericanas tanto en su pluralidad como en sus vínculos, enfocándose en las diásporas afro-latinas. Como uno de los hitos principales de la perspectiva afrodiaspórica descolonizadora que se elabora en el trabajo, se establece un diálogo político epistémico entre el «feminismo de las mujeres de color» con la teoría y la crítica de la modernidad a partir del concepto de colonialidad del poder

  9. Evaluation of CAMP-Like Effect, Biofilm Formation, and Discrimination of Candida africana from Vaginal Candida albicans Species

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    Keyvan Pakshir

    2017-01-01

    Full Text Available Candida africana as a species recovered from female genital specimens is highly close to C. albicans. The present study was conducted to discriminate C. africana from presumptive vaginal C. albicans strains by molecular assay and evaluate their hemolysin activity, biofilm formation, and cohemolytic effect (CAMP with vaginal bacterial flora. A total of 110 stock vaginal C. albicans isolates were examined by HWP1 gene amplification. Hemolysin activity and the ability of biofilm formation were evaluated by blood plate assay and visual detection methods, respectively. Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae were used to evaluate the CAMP-like effects in Sabouraud blood agar media. Based on the size of the amplicons (941 bp, all isolates were identified as C. albicans. All samples were able to produce beta-hemolysin. Moreover, 69 out of 110 of the isolates (62.7% were biofilm-positive, 54 out of 110 Candida isolates (49% demonstrated cohemolytic effects with S. agalactiae, and 48 out of 110 showed this effect with S. aureus (43.6%. All isolates were CAMP-negative with S. epidermidis. We detected all isolates as Candida albicans and almost half of the isolates were CAMP-positive with S. aureus and S. agalactiae, suggesting that these bacteria increase the pathogenicity of Candida in vaginal candidiasis.

  10. Studies on the biocidal and cell membrane disruption potentials of stem bark extracts of Afzelia africana (Smith

    Directory of Open Access Journals (Sweden)

    DAVID A AKINPELU

    2009-01-01

    Full Text Available We had recently reported antibacterial activity in the crude extract of the stem bark of Afzelia africana (Akinpelu et al., 2008. In this study, we assessed the biocidal and cell membrane disruption potentials of fractions obtained from the crude extract of the plant. The aqueous (AQ and butanol (BL fractions exhibited appreciable antibacterial activities against the test bacteria. The minimum inhibitory concentrations of the AQ and BL fractions ranged between 0.313 and 2.5 mg/ml, while their minimum bactericidal concentrations varied between 0.625 and 5.0 mg/ml. Also, the AQ fraction killed about 95.8% of E. coli cells within 105 min at a concentration of 5 mg/ml, while about 99.1% of Bacillus pumilus cells were killed by this fraction at the same concentration and exposure time. A similar trend was observed for the BL fraction. At a concentration of 5 mg/ml, the butanol fraction leaked 9.8 μg/ml of proteins from E. coli cells within 3 h, while the aqueous fraction leaked 6.5 μg/ml of proteins from the same organisms at the same concentration and exposure time. We propose that the stem bark of Afzelia africana is a potential source of bioactive compounds of importance to the pharmaceutical industry.

  11. Evaluation of CAMP-Like Effect, Biofilm Formation, and Discrimination of Candida africana from Vaginal Candida albicans Species

    Science.gov (United States)

    Bordbar, Mahboubeh; Nouraei, Hasti; Khodadadi, Hossein

    2017-01-01

    Candida africana as a species recovered from female genital specimens is highly close to C. albicans. The present study was conducted to discriminate C. africana from presumptive vaginal C. albicans strains by molecular assay and evaluate their hemolysin activity, biofilm formation, and cohemolytic effect (CAMP) with vaginal bacterial flora. A total of 110 stock vaginal C. albicans isolates were examined by HWP1 gene amplification. Hemolysin activity and the ability of biofilm formation were evaluated by blood plate assay and visual detection methods, respectively. Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus agalactiae were used to evaluate the CAMP-like effects in Sabouraud blood agar media. Based on the size of the amplicons (941 bp), all isolates were identified as C. albicans. All samples were able to produce beta-hemolysin. Moreover, 69 out of 110 of the isolates (62.7%) were biofilm-positive, 54 out of 110 Candida isolates (49%) demonstrated cohemolytic effects with S. agalactiae, and 48 out of 110 showed this effect with S. aureus (43.6%). All isolates were CAMP-negative with S. epidermidis. We detected all isolates as Candida albicans and almost half of the isolates were CAMP-positive with S. aureus and S. agalactiae, suggesting that these bacteria increase the pathogenicity of Candida in vaginal candidiasis. PMID:29318048

  12. Caprellidae (Crustacea: Peracarida: Amphipoda) from the Red Sea and Suez Canal, with the redescription of Metaprotella africana and Paradeutella multispinosa.

    Science.gov (United States)

    Zeina, Amr F; Guerra-García, José M

    2016-04-06

    The Caprellidae from the Red Sea are reviewed based on the literature data and new collections from the Hurghada coasts. So far, only six valid species has been reported from the Red Sea and Suez Canal: Caprella equilibra Say, 1818, Hemiaegina minuta Mayer, 1890, Metaprotella africana Mayer, 1903, Paracaprella pusilla Mayer, 1890 and Paradeutella multispinosa Schellenberg, 1928 and Pseudocaprellina pambanensis Sundara Raj, 1927. The type material of M. africana (deposited in the Muséum nacional d'Histoire naturelle, Paris) and Paradeutella multispinosa (deposited in the Museum für Naturkunde, Berlin) are redescribed and illustrated in detail. P. pambanensis and H. minuta were the most abundant species in the collections along the northern coast. Most of the sampling effort has been focused on algae from shallow waters; additional substrates such as sediments, hydroids and coral rubble, especially from areas deeper than 15 meters should be explored. The number of caprellid species in the Red Sea is low compared to adjacent waters, as the Mediterranean Sea. However, further research and more extensive caprellid collections should be conducted along the coasts of Saudi Arabia, Yemen, Sudan and Eritrea, which are still unexplored.

  13. One bis-indole alkaloid-voacamine from Voacanga africana Stapf: biological activity evaluation of PTP1B in vitro utilizing enzymology method based on SPRi expriment.

    Science.gov (United States)

    Wang, Yan-Qiu; Li, Hong-Xiang; Liu, Xiao-Chun; Zhao, Jin-Shuang; Liu, Rong-Qiang; Huai, Wen-Ying; Ding, Wei-Jun; Zhang, Tian-E; Deng, Yun

    2018-05-31

    One known bis-indole alkaloid-voacamine was isolated from Voacanga africana Stapf and Surface Plasmon Resonance imaging (SPRi) exprement showed that this alkaloid could be combine with Protein Tyrosine Phosphatase1B (PTP1B). Then the PTP1B activity inhibition experiment display that the compound showed an outstanding promoting activity to PTP1B.

  14. A Review of the Potential of Phytochemicals from Prunus africana (Hook f. Kalkman Stem Bark for Chemoprevention and Chemotherapy of Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Richard Komakech

    2017-01-01

    Full Text Available Prostate cancer remains one of the major causes of death worldwide. In view of the limited treatment options for patients with prostate cancer, preventive and treatment approaches based on natural compounds can play an integral role in tackling this disease. Recent evidence supports the beneficial effects of plant-derived phytochemicals as chemopreventive and chemotherapeutic agents for various cancers, including prostate cancer. Prunus africana has been used for generations in African traditional medicine to treat prostate cancer. This review examined the potential roles of the phytochemicals from P. africana, an endangered, sub-Saharan Africa plant in the chemoprevention and chemotherapy of prostate cancer. In vitro and in vivo studies have provided strong pharmacological evidence for antiprostate cancer activities of P. africana-derived phytochemicals. Through synergistic interactions between different effective phytochemicals, P. africana extracts have been shown to exhibit very strong antiandrogenic and antiangiogenic activities and have the ability to kill tumor cells via apoptotic pathways, prevent the proliferation of prostate cancer cells, and alter the signaling pathways required for the maintenance of prostate cancer cells. However, further preclinical and clinical studies ought to be done to advance and eventually use these promising phytochemicals for the prevention and chemotherapy of human prostate cancer.

  15. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  16. Development of a novel set of EST-SSR markers and cross-species amplification in Tamarix africana (Tamaricaceae).

    Science.gov (United States)

    Terzoli, Serena; Beritognolo, Isacco; Sabatti, Maurizio; Kuzminsky, Elena

    2010-06-01

    Tamarix plants are resistant to abiotic stresses and have become invasive in North America. Their taxonomy is troublesome, and few molecular makers are available to enable species identification or to track the spread of specific invasive genotypes. Transcriptome sequencing projects offer a potential source for the development of new markers. • Thirteen polymorphic simple sequence repeats (SSRs) markers derived from Expressed Sequence Tags (ESTs) from Tamarix hispida, T. androssowii, T. ramosissima, and T. albiflonum were identified and screened on 24 samples of T. africana to detect polymorphism. The number of alleles per locus ranged from two to eight, with an average of 4.3 alleles per locus, and the mean expected heterozygosity was 0.453. • Amplification products of these 13 loci were also generated for T. gallica. These new EST-SSR markers will be useful in genetic characterization of Tamarix, as additional tools for taxonomic clarification, and for studying invasive populations where they are a threat.

  17. Analysis of essential oils from Voacanga africana seeds at different hydrodistillation extraction stages: chemical composition, antioxidant activity and antimicrobial activity.

    Science.gov (United States)

    Liu, Xiong; Yang, Dongliang; Liu, Jiajia; Ren, Na

    2015-01-01

    In this study, essential oils from Voacanga africana seeds at different extraction stages were investigated. In the chemical composition analysis, 27 compounds representing 86.69-95.03% of the total essential oils were identified and quantified. The main constituents in essential oils were terpenoids, alcohols and fatty acids accounting for 15.03-24.36%, 21.57-34.43% and 33.06-57.37%, respectively. Moreover, the analysis also revealed that essential oils from different extraction stages possessed different chemical compositions. In the antioxidant evaluation, all analysed oils showed similar antioxidant behaviours, and the concentrations of essential oils providing 50% inhibition of DPPH-scavenging activity (IC50) were about 25 mg/mL. In the antimicrobial experiments, essential oils from different extraction stages exhibited different antimicrobial activities. The antimicrobial activity of oils was affected by extraction stages. By controlling extraction stages, it is promising to obtain essential oils with desired antimicrobial activities.

  18. Toxicological parameters of albino rats fed with extruded snacks from Aerial yam (Dioscoria bulbifera) and African breadfruit seed (Treculia africana).

    Science.gov (United States)

    Olatoye, Kazeem K; Arueya, Gibson L

    2018-01-01

    In this study, safety of novel food from aerial yam and Treculia africana , underutilized food materials with high-nutritive value and health benefits were investigated. Animal experiment involving the use of thirty (30) male albino rats was conducted for 28 days.Thereafter, rats in all groups were sacrificed and blood samples collected for biochemical analysis and hematological assay. Some vital organs were harvested and used for histological analysis. Biochemical and hematological parameters were not significantly p  ≤ .05 different among the treatment and controls. However there was an increase in monocytes, which is a reflection of immune boosting potential of the novel snack. No significant pathological changes were observed in liver and kidney of rats fed with this snack. Rats showed no signs of toxicity within the study period. These findings suggest that product may be safe and useful as an Immune adjuvant.

  19. Complete genome sequence of the halophilic bacterium Spirochaeta africana type strain (Z-7692T) from the alkaline Lake Magadi in the East African Rift

    Energy Technology Data Exchange (ETDEWEB)

    Liolios, Konstantinos [U.S. Department of Energy, Joint Genome Institute; Abt, Birte [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Scheuner, Carmen [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Teshima, Hazuki [Los Alamos National Laboratory (LANL); Held, Brittany [Los Alamos National Laboratory (LANL); Lapidus, Alla L. [U.S. Department of Energy, Joint Genome Institute; Nolan, Matt [U.S. Department of Energy, Joint Genome Institute; Lucas, Susan [U.S. Department of Energy, Joint Genome Institute; Deshpande, Shweta [U.S. Department of Energy, Joint Genome Institute; Cheng, Jan-Fang [U.S. Department of Energy, Joint Genome Institute; Tapia, Roxanne [Los Alamos National Laboratory (LANL); Goodwin, Lynne A. [Los Alamos National Laboratory (LANL); Pitluck, Sam [U.S. Department of Energy, Joint Genome Institute; Pagani, Ioanna [U.S. Department of Energy, Joint Genome Institute; Ivanova, N [U.S. Department of Energy, Joint Genome Institute; Mavromatis, K [U.S. Department of Energy, Joint Genome Institute; Mikhailova, Natalia [U.S. Department of Energy, Joint Genome Institute; Huntemann, Marcel [U.S. Department of Energy, Joint Genome Institute; Pati, Amrita [U.S. Department of Energy, Joint Genome Institute; Chen, Amy [U.S. Department of Energy, Joint Genome Institute; Palaniappan, Krishna [U.S. Department of Energy, Joint Genome Institute; Land, Miriam L [ORNL; Rohde, Manfred [HZI - Helmholtz Centre for Infection Research, Braunschweig, Germany; Tindall, Brian [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Detter, J. Chris [U.S. Department of Energy, Joint Genome Institute; Goker, Markus [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Bristow, James [U.S. Department of Energy, Joint Genome Institute; Eisen, Jonathan [U.S. Department of Energy, Joint Genome Institute; Markowitz, Victor [U.S. Department of Energy, Joint Genome Institute; Hugenholtz, Philip [U.S. Department of Energy, Joint Genome Institute; Woyke, Tanja [U.S. Department of Energy, Joint Genome Institute; Klenk, Hans-Peter [DSMZ - German Collection of Microorganisms and Cell Cultures GmbH, Braunschweig, Germany; Kyrpides, Nikos C [U.S. Department of Energy, Joint Genome Institute

    2013-01-01

    Spirochaeta africana Zhilina et al. 1996 is an anaerobic, aerotolerant, spiral-shaped bacte- rium that is motile via periplasmic flagella. The type strain of the species, Z-7692T, was iso- lated in 1993 or earlier from a bacterial bloom in the brine under the trona layer in a shallow lagoon of the alkaline equatorial Lake Magadi in Kenya. Here we describe the features of this organism, together with the complete genome sequence, and annotation. Considering the pending reclassification of S. caldaria to the genus Treponema, S. africana is only the second 'true' member of the genus Spirochaeta with a genome-sequenced type strain to be pub- lished. The 3,285,855 bp long genome of strain Z-7692T with its 2,817 protein-coding and 57 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

  20. Composición de los subproductos de la industrialización de la Palma Africana utilizados en la alimentación animal en Costa Rica

    Directory of Open Access Journals (Sweden)

    Emilio Vargas

    2003-01-01

    Full Text Available Se determinó la composición nutricional y variabilidad de la harina de coquito de palma africana extraída por solvente (HCPAS, la harina de coquito de palma africana de extracción mecánica (HCPAM, el coquito integral de la palma africana (CIPA, la grasa cruda de la palma africana (GCPA y los ácidos grasos libres de la palma africana (AGLPA. Los resultados indicaron que la HCPAS y la HCPAM producidas en Costa Rica tienen una composición nutricional semejante a la reportada en la literatura internacional, excepto por un mayor contenido de grasa residual, con valores de 3,3 y 13,2% para los productos locales en comparación con 1,75 y 10,94% para los producidos en otros países. Asimismo, se observó una mayor variabilidad en el contenido de fibra y grasa de los productos locales. El CIPA es un material con un alto contenido de grasa (46-49%; 8-9% de proteína cruda y 10- 12% de fibra; lo cual lo convierte en un producto de un alto potencial nutricional. Los valores de energía digestible en cerdos fueron de 3000, 3215 y 4780 Kcal kg-1 de MS para la HCPAS, HCPAM y el CIPA, respectivamente. En aves la energía metabolizable aparente fue de 1399, 1789 y 4230 Kcal kg-1 de MS. La GCPA y los AGLPA mostraron una composición típica de ácidos grasos para estos materiales, con una relación ácidos grasos insaturados y ácidos grasos saturados de 1,01 y 0,78, respectivamente. El contenido de energía digestible de la GCPA en cerdos fue de 8064 Kcal kg-1 de MS y la energía metabolizable aparente en aves fue de 8615 Kcal kg-1 de MS. En los AGLPA, los valores observados fueron de 6859 y 5068 Kcal kg-1 de MS. Se sugiere valores de los niveles por utilizar en la formulación de raciones para diferentes especies de animales de esos subproductos.

  1. Géneros narrativos nas literaturas africanas de língua portuguesa – entre a tradição africana e o “cânone ocidental”

    Directory of Open Access Journals (Sweden)

    Inocência Mata

    2015-11-01

    Full Text Available Depois do golpe de Estado em Portugal, a 25 de Abril de 1974, começámos, nos países africanos ainda colónias de Portugal, a estudar os “nossos” escritores. Andava eu ainda no liceu e naquele tempo não me lembro de termos estudado autores brasileiros e muito menos africanos. Por isso, na altura, uma questão que me intrigou q uando tive contacto com os primeiros textos africanos, foi a palavra estória – em vez de conto – para referir narrativas curtas. Primeiro pensei tratar-se de mais um “africanismo” (explicação então em voga para qualquer “desvio”; depois, quando fui aprofundando o estudo das literaturas africanas, na Faculdade de Letras da Universidade de Lisboa, como aluna do Professor Manuel Ferreira, esta questão nunca foi referida como “problema” e, por isso, a designação “naturalizou-se”… Até que me tornei estudiosa dessas literaturas, já então conhecedora da presença do termo na literatura brasileira.

  2. Pequeños productores, reestructuración y expansión de la palma africana en Chiapas

    Directory of Open Access Journals (Sweden)

    Héctor B. Fletes Ocón

    2013-01-01

    Full Text Available En el contexto del dinamismo y contradicciones del sector agroalimentario, en la actualidad los pequeños productores son impulsados a emprender una reestructuración de sus prácticas productivas, a través de la plantación de cultivos orientados a biocombustibles, como el de la palma africana. En este artículo se analizan los procesos de reestructuración productiva, promovida por corpora-ciones de distinto origen y por el Estado, y las acciones realizadas por pequeños productores en un municipio con alta marginación, localizado en una región agroexportadora de Chiapas. Se revisan las contradicciones sociales y ambientales de este cambio y sus implicaciones a futuro, en términos del desarrollo agrícola y alimentario nacional. La expansión de este cultivo acentúa las desigualdades sociales, degrada los recursos naturales, utiliza mucha energía fósil, impulsa la concentración de la tierra, debilita los sistemas locales de provisión de alimentos y reduce los márgenes del valor generado en la cadena agroalimentaria para los pequeños productores.

  3. Fabricación de adoquines para uso en vías peatonales, usando cuesco de palma africana

    Directory of Open Access Journals (Sweden)

    Jorge Elías Buzón Ojeda

    2010-01-01

    Full Text Available Con el fin de mejorar la calidad de vida en sectores vulnerables de la sociedad, las investigaciones actuales han centrado sus esfuerzos en desarrollar no solo técnicas y procesos novedosos de construcción, sino que han reorientado sus esfuerzos en crear materiales de construcción no convencionales, que ayuden a rebajar costos y propicien el de la industria de la construcción. Actualmente las plantas productoras de aceite que usan la palma africana como materia prima enfrentan un grave problema, al no saber qué hacer con el desecho final del proceso de producción del aceite. Este desecho posee características mecánicas interesantes: una alta dureza, alta resistencia al desgaste y bajo peso o poca densidad. Estas características la han sabido aprovechar los cultivadores e industriales, pues en lugar de llevar este excedente a botaderos, lo arrojan sobre las vías internas de las plantaciones como material base o capa de rodadura, mejorando así la movilidad de las mismas. Este artículo presenta los satisfactorios resultados parciales de la investigación, que nos motivan a continuar trabajando en este tema.

  4. Propuesta metodológica para la gestión formativa socio-cultural profesional en las universidades africanas

    Directory of Open Access Journals (Sweden)

    MsC. Moussa Moustapha

    2015-10-01

    Full Text Available En la actualidad, para un desarrollo económico, social, cultural, político y profesional sustentable en los países subdesarrollados, es imprescindible que sus instituciones de la educación superior, como entidades sociales, tengan sus propios modelos pedagógicos y metodológicos, conforme a las realidades de sus contextos. Ello le permite no solamente jugar su rol social, involucrándose más en el desarrollo y transformación de su contexto, sino encausar una formación de profesionales que trascienden su tiempo, comprometidos, auténticos, flexibles, competitivos y orgullosos de sus tradiciones y costumbres.En el presente trabajo, proponemos una metodología de gestión formativa socio-cultural profesional para las universidades africanas, cuyo objetivo es contextualizar los procesos universitarios africanos. Ella es premisa de una valoración científica de los realidades socio-culturales contextuales, que desde sus raíces humanistas, ancestrales, milenarias y sus riquezas como potencialidades socio-culturales asienten el desarrollo de una identidad y autenticidad formativa profesional y un desarrollo cultural universitaria para el empoderamiento del proceso.

  5. Paz y seguridad humana en África: una visión desde la Unión Africana

    Directory of Open Access Journals (Sweden)

    Jerónimo Delgado

    2009-11-01

    Full Text Available En este artículo se analizan las diferentes iniciativas que ha tenido el continente africano en materia de solución de conflictos y consolidación de la paz desde la perspectiva de la seguridad humana. En la primera parte, se identifican los componentes de la seguridad humana y los factores de inseguridad a los que se exponen los individuos en África, para luego examinar los avances del marco legal de la Unión Africana en la prevención de conflictos con énfasis en la seguridad de los individuos.La segunda parte contiene un estudio de las medidas enmarcadas dentro de la seguridad humana con las que cuentan los estados africanos y la comunidad internacional para la adecuada protección de los individuos, mientras se da un acercamiento entre las partes del conflicto para alcanzar el fin de las hostilidades. Finalmente, se afirma que África reconoce que la seguridad de sus ciudadanos es viable si se entienda que ésta es una responsabilidad compartida por todo el continente, en donde el individuo juega un papel central.

  6. COMPORTAMENTO DA Cordia africana Lam. CULTIVADA EM SOLO CONTAMINADO POR METAIS PESADOS E TRATADO COM MATERIAIS AMENIZANTES

    Directory of Open Access Journals (Sweden)

    Ana Carolina Callegario Pereira

    2013-01-01

    Full Text Available This study aimed to evaluate the remediation of two soils contaminated with heavy metals from soil excavations, located near the port of Itaguaí, through the techniques of chemical immobilization and phytostabilization using the species Cordia africana. The data were collected in the ore courtyard from ‘Companhia Siderúgica Nacional’ (CSN, in the port of Itaguaí, Rio de Janeiro state. In order to reduce the solubility of heavy metals present in these substrates, two industrial waste products produced by CSN were used as ameliorating products, the steelmaking slag and the mill scale, in different concentrations. The plant species was considered with potential to be used in programs of phytostabilization, due to its heavy metal tolerance studied and to high accumulation of such elements in roots and stem. In the substrate of low combination, the lowest accumulation of zinc and cadmium in stems and leaves occurred with the use of 4% of soothing. In the substrate of high accumaltion it was 6%.

  7. DE MANDELA À ZUMA: A IMPORTÂNCIA DO ATLÂNTICO SUL NA POLÍTICA EXTERNA SUL-AFRICANA

    Directory of Open Access Journals (Sweden)

    Anselmo Otavio

    2017-09-01

    Full Text Available O artigo busca compreender a importância do Atlântico Sul na política externa sul-africana pós-apartheid. Baseando-se em ampla bibliografia relacionada ao tema, busca-se defender a hipótese de que o aumento do interesse pelo Atlântico Sul em verdade é resultado da valorização por parte da África do Sul das relações Sul-Sul.

  8. Evaluación de Varios Insecticidas para el Control del Cephaloleiaspcerca avagelineataPic, Plaga de la Palma Africana

    Directory of Open Access Journals (Sweden)

    Urueta Sandino Eduardo

    1974-04-01

    Full Text Available Resumen. Se efectuaron varios ensayos para determinar el efecto de carbofuran 1.0, 1.5 y 2. 0 kg I. A./ha; carbaril 1.5 y 2. 0 kg I. A. /ha; lindano 1.0 y 1.5 kg I. A. /ha; diazinon 0.5 lt I. A./ha; dicrotofos 0. 5 lt I. A. /ha; fosfamidon 0.6 lt. I. A/ha; y fention 0.5 lt I. A./ha, sobre adultos y larvas de Cephaloleiasp. cerca avagelineataPic., una plaga de la palma africana en Colombia. Todos los insecticidas fueron efectivos para controlar larvas de Cephaloleiasp. en cogollos, hasta por periodos de más de 30 días. El carbofuran 2.0 kg I. A./ha carbaril 2.0 kg l . A./ha y lindano 1. 5 kg I.A. /hafueron los productos más eficientes para controlar adultos de Cephaloleia. sp. protegiendo por 15 días las hojas más jóvenes. Dicrotofos 0.5 lt I. A./ha; diazinon0.5 lt l. A./ha; fention 0.5 itI. A./ha y fosfamidon 0.6 lt I. A/ha, aparentemente no fueron efectivos para controlar las formas adultas de Cephaloleiasp. Ninguno de los insecticidas fue fitotóxico para la palma africana. /Abstract. Several tests were carried out to determine the effectiveness of carbofuran 1. 0, 1.5 and 2.0 kg A.I./ha; carbaryl 1.5, 2.0 kg. A.I./ha; lindane 1.0, 1.5 kg. A.I./ha; phosphamidon 0.6 lt. A.I./ha; fenthion 0.5 lt. A.I./ha; dicrotophos 0.5 lt. A.I /ha; diazinon 0.5 lt. A.I./ha on larvae and adults of Cephaloleia. sp. near vagelineata Pic a Chrysomelidae that affects young oil palm (Elaeisguineensis leaves in Colombia. All of these insecticides controlled well Cepbaloleia sp. larvae for periods over a month. carbofuran 2 kg. A.I./ha; carbaryl 2kg. A.I./ha and lindane 1.5 kg. A. I./ha gave the best control of Cephaloleia. sp. adults, protecting young oil palm leaves up to 15 days. Dicrotophos 0.5 lts. A.I./ha; fenthion 0.5 lt. A. I./ha; phosphamidon 0.6 lt. A.I./ha; diazinon 0.5 lt. A.I./ha; apparently were not effective to control adults of Cephaloleia sp. None of the insecticides tested showed to be phytotoxic to the oil palm.

  9. BREADFRUIT (Treculia africana MARKETING ACTIVITIES AND RETURNS IN AHIAZU MBAISE LOCAL GOVERNMENT AREA, OF IMO STATE, NIGERIA

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    Ogbonna Christopher EMEROLE

    2013-12-01

    Full Text Available This study on marketing of breadfruits (Treculia africana and returns was done in Ahiazu Mbaise local Government area of Imo State, Nigeria. The specific objectives of the study were to describe socio-economic characteristics of respondents (sellers and buyers of African breadfruit; identify value-chain activities available in processing and its storage in compliance with consumers’ order and preferences; determine factors influencing decision to supply African breadfruit; and constraints with its post-harvest management in the study area. Three-stage random sampling technique was used in selecting locations and respondents through which eighty (80 farm households who gather/harvest, process and sell breadfruits were selected and interviewed with structured questionnaire. Data collected were analyzed using descriptive statistics, and probit regression model. Result revealed that 65.80% of the respondents were females and 81.20% of them were married with mean household size of 9 members. Their literacy level was high as 97.6% of them had at least primary education. Predominant marketing activities were fruit gathering/harvesting, processing, storage and packaging, transportation, and sales. Socio-economic factors of gender, household size, income, level of education, years of farming experience and labour significantly influenced supply of breadfruits to consumers with challenges of seasonal scarcity, and tedious methods of processing deterring the enterprise in the area. We recommended provision of credit support to enable fruit gatherers purchase and use shelling machines and good storage facilities to smooth any fluctuations in supplies during off-seasons and help fight overdependence of households on roots and tubers.

  10. HONGOS MICORRÍCICO-ARBUSCULARES EN LA PRODUCCIÓN DE VIOLETA AFRICANA EN UN SISTEMA DE MANEJO TRADICIONAL

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    Ramón Zulueta-Rodríguez

    2013-01-01

    Full Text Available Se determinó el efecto de la inoculación de violeta africana ( Saintpaulia ionantha Wendl. con hongos micorrícico-arbusculares (HMA en un vivero comercial bajo el sistema de cultivo del productor. Se probaron dos presentaciones del inóculo, raíces frescas (IT e inoculante encapsulado en perlas de alginato de calcio (IE. Los tratamientos establecidos fueron plantas inoculadas con cada uno de los inóculos (IT e IE, plantas fertilizadas sin inocular (F, plantas inoculadas + fertilizante (IT+F e IE+F y plantas testigo (T. Las variables evaluadas 90 y 180 días después de la inoculación (DDI fueron área foliar, número de hojas, de botones florales y de flores, así como la longitud de raíz colonizada, peso seco de pecíolos, hojas y raíces al final del experimento (180 DDI. El análisis estadístico indicó diferencias altamente significativas entre los tratamientos a los 90 DDI para área foliar, número de botones florales y de flores (ANOVA, P ≤ 0.01, respuesta que prevaleció hasta los 180 DDI con respecto a las plantas testigo (ANOVA, P ≤ 0.01. En general, la interacción de los HMA con el fertilizante promovió una floración prematura, lo cual indica que el uso de estos microorganismos puede considerarse una alterna - tiva biotecnológica factible de incorporar en estos sistemas de producción.

  11. Geografías urbanas: representación e identidad en la literatura africana en español

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    M’bare N’gom

    2012-12-01

    Full Text Available Este trabajo estudia las representaciones de las geografías urbanas y sus problemáticas en la literatura africana de expresión castellana. Para tal efecto propone la representación de las realidades urbanas como espacios de experiencias de vida heterogéneas, ya sean culturales, políticas o de renegociación de identidad. Igualmente examina cómo esa geografía urbana se configura como espacio que se presta a la articulación de una multitud de discursos y reinterpretaciones de la realidad urbana y urbanística, que obligan en este caso al sujeto migrante africano a embarcarse en un proceso de reterritorialización desde la transterritorialidad del desplazamiento, como estrategia de supervivencia en ese espacio ajeno y dislocado que es la ciudad.This study explores the representations of urban geography and its problematic in African literature in Spanish. It intends to examinate the representation of urban realities as spaces of heterogeneous experiences, be they cultural, political, or renegociation of identity. Along those lines, this study will discuss how urban geography becomes a space that allows a multitude of negociations, as well as the articulation of a variety of discourses and reinterpretations of urban and urbanistic reality that oblige the African migrant subject, in this case, to engage in a process of reterritorialization from the transterritoriality of displacement, as a strategy for survival in an alien and dislocated space such as the City.

  12. Migración africana y formación social en las Américas, 1500-2000

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    Moya, José C.

    2012-08-01

    Full Text Available Around 11 million Africans reached the New World between 1500 and 1866 in what constitutes the first massive transoceanic migration in the history of humanity. This article approaches that movement from the perspective of the history of migrations and socio-racial formations in the Americas. The first part establishes the origins, timing, and geographic distribution of the arrivals using a database with information on some 35,000 slave ship voyages. We go on to analyze how this determined the demographic impact, socio-economic development, African cultural presence, adaptation and acculturation strategies, and the construction of racial taxonomies and identities in the receiving regions.

    Unos 11 millones de africanos llegaron al Nuevo Mundo entre 1500 y 1866 en lo que constituye la primera migración masiva transoceánica en la historia de la humanidad. Este artículo estudia ese movimiento desde la perspectiva de la historia de las migraciones y formaciones socio-raciales en las Américas. La primera parte establece el origen, ritmo temporal y distribución geográfica de las llegadas empleando una base de datos que contiene información sobre unos 35.000 viajes de barcos negreros. Sobre esta base, se analiza el impacto demográfico, el desarrollo socioeconómico, la presencia cultural africana, las estrategias de adaptación y aculturación, y la construcción de taxonomías e identidades raciales en las regiones receptoras.

  13. Plantas de la Diáspora Africana en la botánica americana de la fase Colonial

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    Judith Carney

    2003-12-01

    botany.//Las plantaciones revolucionarias y los intercambios ecológicos que acompañaron la expansión marítima europea después de 1492 son muy apreciados en la actualidad. De igual manera lo son los significados de las nuevas plantas dentro de la sociedad europea en tanto que modificaron preferencias culinarias, la economía y el comercio incluso más allá de las fronteras del viejo continente. El papel del maíz amerindio y de la mandioca en África occidental ha recibido una amplia atención así como el arroz asiático dentro de la región. Pero la literatura sobre el intercambio de alimentos sigue siendo muy escasa en cuanto a la difusión de plantas africanas y a las vías mediante las que dicha dispersión fue posible. Para estudiar este problema es necesario atender al comercio de esclavos y a la forma en la que éstos pudieron establecer preferencias alimentarias en las Américas. Este ensayo examina las plantas de origen africano que se convirtieron en productos esenciales dentro de las economías en la era de las plantaciones esclavistas. Tres centros de domesticación agrícola en el África Subsahariana contribuyeron a la diversidad de recursos que ayudaron a la subsistencia de millones y que fueron llevadas más allá del Atlántico debido al comercio de esclavos. La plantación de dichos productos se llevó a cabo en las Américas gracias a los “jardines botánicos” de los desposeídos: los campos de subsistencia de las plantaciones, jardines, patios y en parcelas agrícolas de las comunidades mulatas. Al llamar la atención sobre la Diáspora africana de plantas se abre la posibilidad de comprender los sistemas de conocimiento africanos. La expresión de dichos sistemas se refleja en las relaciones de poder prevalecientes, en las preferencias de alimentos, la identidad cultural, y las luchas por el proceso de trabajo.Al mostrar las plantas africanas establecidas en América, este trabajo busca corregir las distorsiones en las narrativas del

  14. Antibacterial activity of crude methanolic extract and various fractions of Vitex agnus castus and Myrsine africana against clinical isolates of Methicillin Resistant Staphylococcus aureus.

    Science.gov (United States)

    Ahmad, Bashir; Hafeez, Nabia; Ara, Gulshan; Azam, Sadiq; Bashir, Shumaila; Khan, Ibrar

    2016-11-01

    Staphylococcus aureus is a nosocomial pathogen that resides in the soft tissues causing many diseases. The current study was conducted to determine the prevalence of Methicillin Resistant S. aureus (MRSA) in ear discharge and pus of patients and antibacterial activity of crude methanolic extract (Cr. MeOH Ext.) and various fractions of M. Africana and V. agnus castus against clinical isolates of MRSA. A total of 40 samples were collected from ear, nose and throat (ENT) outpatient department and wards of Khyber Teaching Hospital (KTH), Peshawar. Out of 40 samples, 36 (90%) samples showed growth on Mannitol Salt Agar (MSA) media out of which 9(25%) were MRSA and the remaining 27(75%) were methicillin susceptible S. aureus (MSSA). A good antibacterial activity was observed for the Cr. MeOH Ext. (76.1%) and ethyl acetate (EtOAc) fraction of V. agnus castus against S11 (71.4%). The n-hexane fraction also showed good antibacterial effect (70%) against S 26 . The chloroform (CHCl3), butanol (BuOH) and aqueous fractions of M. africana showed good antibacterial activity against S 11 (71.4%), S32 (70%) and S 26 (75%), respectively. The above results revealed that the selected plants can be further utilized for isolation of the active ingredients as the crude extracts were found good for inhibition of MRSA.

  15. Vegetative Propagation Trial of Prosopis africana (Guill. et Perr. Taub. by Air Layering under Sudano-Sahelian Climate in the South-Central Niger

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    Laouali Abdou

    2015-01-01

    Full Text Available Prosopis africana is a species of great socioeconomic importance but threatened with extinction in Niger because of overuse and regeneration problem. This study, conducted in the Maradi (Niger area, precisely at El Gueza in the south of Gazaoua department, aims to evaluate the vegetative propagation capacity of P. africana by air layering under the Sudano-Sahelian climate of the south-central Niger. A ring of bark was taken on each selected branch and the wound was covered with a black plastic filled with a damp mixture of soil and wood debris. The chosen parameters are the diameter class and the position on the branch. In all, 60 branches were treated and followed for 130 days: 28.33% produced shoots and there was no significant difference between the diameter classes and between the positions. These results show that propagating trees of the species by air layering is possible and this technique can be used to multiply and keep this species, which will reduce the regeneration problem linked to a low seed germination rate.

  16. Rhythm experience and Africana culture trial (REACT!): A culturally salient intervention to promote neurocognitive health, mood, and well-being in older African Americans.

    Science.gov (United States)

    Lukach, Alexis J; Jedrziewski, M Kathryn; Grove, George A; Mechanic-Hamilton, Dawn J; Williams, Shardae S; Wollam, Mariegold E; Erickson, Kirk I

    2016-05-01

    The Rhythm Experience and Africana Culture Trial (REACT!) is a multi-site randomized controlled intervention study designed to examine the efficacy of using African Dance as a form of moderate-intensity physical activity to improve cognitive function in older African Americans. African Americans are almost two times more likely than Caucasians to experience cognitive impairment in late adulthood. This increased risk may be attributed to lower level and quality of education, lower socioeconomic status, and higher prevalence of vascular diseases, type 2 diabetes, hypertension, and obesity, all of which are recognized as risk factors for dementia. Fortunately, interventions targeting cardiovascular health (i.e., physical activity) are associated with improved neurocognitive function and a reduced risk for dementia, so African Americans may be particularly suited for interventions targeting cardiovascular health and cognitive function. Here, we describe a randomized intervention protocol for increasing physical activity in older (65-75years) African Americans. Participants (n=80) at two study locations will be randomized into one of two groups. The treatment group will participate in African Dance three times per week for six months and the control group will receive educational training on Africana history and culture, as well as information about health behaviors, three times per week for six months. If successful, the REACT! study may transform community interventions and serve as a platform and model for testing other populations, age groups, and health outcomes, potentially identifying novel and creative methods for reducing or eliminating health disparities. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Effet de prétraitements des semences sur la germination de Prosopis africana (Guill., Perrot. et Rich. Taub., (Césalpiniacées

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    M'po Ifonti M'po

    2009-01-01

    Full Text Available Effect of Seed Treatments on the Germination of Iron Tree Prosopis africana (Guill., Perrot. et Rich. Taub. The effect of four seed treatments (i soaking in concentrate sulphuric acid for 15 mn, (ii soaking in hot water at 100 oC for 3 mm followed by in immersion into tap water for 24 hours, (iii scarification with razor blade (iv no treatment on the germination of Prosopis africana seeds was evaluated on two types of growing substrate: erosion sand and ferrallitic soil. Non treated seeds gave the highest rates of germination on the two types of growing substrate (100% on erosion sand and 89% on ferrallitic soil and by much longer duration of germination compared to treated seeds (46 days on erosion sand and 42 days on ferrallitic soil. Overall, germination is better (rates and speed on erosion sand. Treatments of the seeds in concentrate sulphuric acid are prejudicial to the survival of the embryo and yield low germination rates (30% on erosion sand and 20% on ferrallitic soil. Scarification by razor blade and soaking in hot water at 100 oC gave the highest germination rate (85%, 18 days after sowing on erosion sand and allowed to accelerate the germination. Because of their simplicity and their low cost, these two seed treatments can be recommended for planters and the use of erosion sand for the sowing.

  18. Phytochemical screening by LC-MS and LC-PDA of ethanolic extracts from the fruits of Kigelia africana (Lam.) Benth.

    Science.gov (United States)

    Costa, Rosaria; Albergamo, Ambrogina; Pellizzeri, Vito; Dugo, Giacomo

    2017-06-01

    Kigelia africana is a tree native to Africa, with a local employment in numerous fields, ranging from traditional medicine to cosmetics and religious rituals. Parts of the plant generally used are stem bark, fruits, roots and leaves. The fruits, which have a singular 'sausage' shape, are widely exploited by local folk, in particular for applications/products involving genito-urinary apparatus of both human genders. The scope of this work was to make a consistent chemical investigation on this plant species, in order to clarify and increase the information at present available in literature. To this aim, ethanolic extracts of K. africana fruits were analysed by high-performance liquid chromatography with photodiode array (HPLC-PDA) and electrospray-mass spectrometry (HPLC-ESI-MS) detection, revealing the presence of polyphenols and iridoids. The two detection systems used along with standard co-injection and comparison with previous reports, led to the identification and quantification of six phenolic compounds and three iridoids.

  19. SETTING HEALTH PRIORITIES IN RESEARCH: AN AFRICAN PERSPECTIVE ESTABLECIMIENTO DE PRIORIDADES DE SALUD EN INVESTIGACIÓN: UNA PERSPECTIVA AFRICANA ESTABELECIMENTO DE PRIORIDADES DE SAÚDE NA PESQUISA: UMA PERSPECTIVA AFRICANA

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    Angela Amondi Wasunna

    2004-01-01

    édicas diseñadas para mejorar la salud y, en la mayoría de los casos, requiere participación de seres humanos como sujetos de investigación. Éstos no pueden, sin embargo, verse en aislamiento; son parte de una comunidad, lo que implica una pregunta: ¿cómo se benefician las comunidades con la investigación que tiene lugar en ellas? En el mundo de la ética de la investigación se ha convertido en un mantra decir que las comunidades deben beneficiarse con los resultados positivos de la investigación. Esta norma ética es importante; sin embargo, mi artículo se enfoca en la participación de la comunidad antes de que se realice la investigación. Usando ejemplos de África como casos, examinaré hasta qué punto se incluye a las comunidades al establecer la agenda de investigación en salud, y si se les consulta al fijar prioridades. Puede que la investigación que se realiza en varias comunidades africanas responda a sus necesidades de salud; sin embargo, ¿cuán prioritarios son estos problemas para cada comunidad? ¿Son postergadas otras necesidades importantes de salud? Mientras que se ha dicho mucho sobre proveer tratamiento para la comunidad entera después de que la investigación ha demostrado ser eficaz, no se ha dicho lo suficiente sobre quién decide cuál investigación es importante para la comunidad antes de que se realiceAtualmente se realiza muita pesquisa biomédica e epidemiológica na África que é tanto horizontal (envolvendo pesquisadores locais e instituições regionais de pesquisa como vertical (envolvendo patrocinadores e colaboradores internacionais. A pesquisa é o caminho necessário para se conquistar inovações biomédicas para melhorar a saúde e, na maioria dos casos, exige a participação de seres humãos como sujeitos de pesquisa. Estes não podem ser vistos isoladamente, são parte de uma comunidade, o que implica um questionamento: que benefícios a pesquisa traz para a comunidade? No mundo da ética da pesquisa se transformou um

  20. Avaliação nutricional da grama-estrela cv. Africana para vacas leiteiras em condições de pastejo Nutritional analysis of stargrass cv. Africana for dairy cattle under rotational grazing

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    Maurício Gomes Favoreto

    2008-02-01

    Full Text Available Objetivou-se avaliar nutricionalmente a grama-estrela (Cynodon nlemfuensis cv. Africana utilizada sob pastejo rotacionado por vacas leiteiras. Dez vacas mestiças foram manejadas em 2 ha de grama-estrela e divididas em 11 piquetes/ha. O período de pastejo foi de três dias e os 30 subseqüentes foram destinados à recuperação da pastagem. Durante o período experimental, os animais foram ordenhados duas vezes ao dia e receberam suplementação com 2 kg de concentrado. Amostras representativas do pasto ingeridas (extrusa foram colhidas para determinação de sua composição nutricional. O consumo de matéria seca (MS pelos animais foi estimado utilizando-se cromo e a MS indigestível como indicadores externo e interno. O desempenho individual das vacas foi avaliado pela produção de leite diária e pela pesagem dos animais. A dinâmica da matéria alimentar foi estimada com base nas técnicas in vitro gravimétricas, de produção cumulativa de gases da fermentação microbiana e da estimativa da cinética de passagem das fases sólida e líquida. A quantidade de energia líquida total (ELt, em MJ/dia, atendeu à demanda energética exigida pelos animais. Os valores de proteína metabolizável (PM preditos corresponderam ao suprimento de 91% da PM exigida por esses animais. As predições das exigências em macrominerais atenderam apenas 75% do Ca exigido, mas atenderam às exigências dos demais macrominerais. A grama-estrela atende à demanda energética nutricional de mantença e produção de 11,7 kg de leite por dia. Nas circunstâncias estudadas, é necessário suplementar nutrientes que complementem a PM e Ca não atendidos completamente. O teor e as características cinéticas da fibra não causam repleção ruminal e restrição sobre o consumo de vacas leiteiras em pastejo.An nutritional analysis of stargrass cv. Africana fed dairy cattle under rotational grazing was evaluated in this research. Ten Holstein-Zebu crossbred cows were

  1. Evaluación agronómica y nutricional del pasto estrella africana (cynodon nlemfuensis En la zona de monte verde, puntarenas, Costa Rica. II. valor nutricional

    Directory of Open Access Journals (Sweden)

    Luis Villalobos

    2014-01-01

    Full Text Available Se analizó el valor nutricional del pasto estrella africana ( Cynodon nlemfuensis a lo largo de 2 años en muestreos bimensuales, en 4 fincas comerciales de ganado lechero ubicadas en los cantones de Tilarán y Central (latitud 10°20’ N, longitud 84°50’, altitud 800 a 1200 msnm de las provincias de Guanacaste y Puntarenas, respectivamente. Las muestras se recolectaron en el aparto siguiente a ser pastoreado y se utilizó una altura de cosecha de 10 cm, para simular el pastoreo que hacen los animales. La composición nutricional promedio para los 2 años de evalua - ción fue de 23,57% MS, 20,27% PC, 2,67% EE, 10,97% cenizas, 64,21% FDN, 34,95% FDA, 4,06% lignina y 68,02% DIVMS y su contenido energético para las variables de TND, ED, EM, EN L (3X y EN G fue 61,37%; 2,71; 2,05; 1,25 y 0,78 Mcal.kg -1 de MS, respectivamente. El valor nutricional del pasto estrella africana varió a lo largo del año como resultado de la climatología de la zona de Monteverde, siendo las fincas con influencia de la vertiente del Pacífico las de menor afectación en la calidad del forraje. El pasto estrella africana mostró un contenido de PC superior a lo reportado para dicha especie y, en general, para pastos tropicales, por lo cual no es limitante para la producción láctea, y la suplementación del ganado lechero en la zona debe utilizar fuentes que permitan una utiliza - ción eficiente del N soluble a nivel ruminal. La rotación del pasto estrella cada 25 días debe ser flexible para permitir, en conjunto con programas de fertilización, optimizar la productividad de las pasturas y su persistencia.

  2. Evaluación del cuesco de palma africana y del carbón del cerrejón para producir carbón activado

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    Anundo Polanía León

    2010-05-01

    Full Text Available Se produjeron carbones activados a partir de carbón de El Cerrejón y del Cuesco de Palma Africana mediante activación con vapor de agua y KOH, a 700 y 800 ó 900°C variando la relación activante/carbonizado y el tiempo de activación. Los tiempos de activación a los que se desarrolla mayor área superficial son mucho más cortos con el vapor de agua que con el KOH. Al activar con este último se obtienen valores de área superficial similares errlas dos materias primas, según la temperatura de trabajo, mientras que la activación con vapor de agua, presenta características totalmente diferentes. La activación del Cuesco de Palma Africana con KOH, produce carbones esencialmente microporosos, mientras que con vapor de agua, produce carbones activados con una apreciable mesoporosidad favorecida por el incremento de la temperatura. La activación del carbón de El Cerrejón con KOH o vapor de agua produce carbones activados microporosos. En líneas generales se puede decir que el tipo de textura porosa obtenida en la producción de un carbón activado, es función no sólo de los agentes activantes utilizados, sino también del tipo u origen de la materia prima, mientras que la calidad del carbón activado, (área superficial total, es función del tiempo y de la temperatura de activación, al menos con los materiales de partida usados en este trabajo.

  3. Consumo da costa africana: comunicações entre os portos turísticos sul-africanos do oceano Índico

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    Pamila Gupta

    2015-12-01

    Full Text Available Do início até meados do século XX, os cruzeiros turísticos ao longo da costa sul-africana eram uma atividade de lazer popular, empreendida pelas elites (brancas europeias (predominantemente os britânicos, americanas e sul-africanas, com paradas que incluíam diversas cidades portuárias do oceano Índico, como Cidade do Cabo e Durban, na África do Sul, e Lourenço Marques e Beira, no Moçambique português. Considerando as cidades portuárias anteriormente mencionadas como cidades-gêmeas em relação aos seus entrelaçados passados coloniais e turísticos e como funcionando dentro de um “corredor cultural” regional distinto (NUTALL, 2009 da África do Sul, este artigo explora uma série de portos de lazer interligados via cruzeiros de passageiros. A base da minha navegação histórica são os anuários de turismo produzidos pelas companhias de cruzeiro marítimo Union-Castle Line e serviço Round África em 1939 e 1949, respectivamente. A justificativa é que esses guias de viagem servem como entrada ao microcosmo cosmopolita de barcos de cruzeiro, o que os torna inestimáveis para entender a história do lazer (concomitantemente aos bens de consumo e publicidade relacionados na África do Sul.

  4. Calorific value of Prosopis africana and Balanites aegyptiaca wood: Relationships with tree growth, wood density and rainfall gradients in the West African Sahel

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Carmen Sotelo; Weber, John C. [World Agroforestry Centre (ICRAF), Sahel Office, B.P. E 5118 Bamako (Mali); Silva, Dimas Agostinho da; Bolzon de Muniz, Graciela Ines [Universidade Federal do Parana (UFPR), Av. Lothario Meissner, 900, CEP.: 80270-170-Curitiba (Brazil); Garcia, Rosilei A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Instituto de Florestas, Departamento de Produtos Florestais, BR 465, km 07, 23890-000, Seropedica, Rio de Janeiro (Brazil)

    2011-01-15

    Prosopis africana and Balanites aegyptiaca are native tree species in the West African Sahel and provide wood for fuel, construction and other essential products. A provenance/progeny test of each species was established at one relatively dry site in Niger, and evaluated at 13 years. Gross calorific value of the wood was determined for a random sample of trees in each test: gross CV and CVm{sup 3} = gross calorific value in MJ kg{sup -1} and MJ m{sup -3}, respectively. The major objectives were to determine if gross CV was positively correlated with wood density and tree growth, and if gross CV and/or CVm{sup 3} varied with rainfall gradients in the sample region. Provenances were grouped into a drier and more humid zone, and correlations were computed among all trees and separately in each zone. Results indicated that gross CV was not significantly correlated with density in either species. Gross CV was positively correlated with growth of P. africana (but not B. aegyptiaca) only in the drier zone. Gross CVm{sup 3} was positively correlated with growth of both species, and the correlations were stronger in the drier zone. Multiple regressions with provenance latitude, longitude and elevation indicated that provenance means for gross CV increased, in general, from the drier to the more humid zones. Regressions with gross CVm{sup 3} were not significant. Results are compared with earlier research reports from the provenance/progeny tests and with other tropical hardwood species; and practical implications are presented for tree improvement and conservation programs in the region. (author)

  5. of Spirostachys africana complicated

    African Journals Online (AJOL)

    C Scott, FCPaed (SA). Department of Paediatrics, Red Cross War Memorial Children's Hospital and University of Cape Town. N P Khumalo, MB ChB, .... Jeung YJ, Lee JY, Oh MJ, Choi DC, Lee BJ. Comparison of the causes and clinical features of drug rash with eosinophilia and systemic symptoms and Stevens-Johnson ...

  6. Matrices coloniales y diásporas africanas: Hacia una investigación de las culturas negra y mulata en la Nueva Granada

    Directory of Open Access Journals (Sweden)

    Rafael Antonio Díaz Díaz

    2003-12-01

    estará definido por la teoría de la cultura colonial. Posteriormente, me concentraré en el campo de las etapas transatlánticas como una escena fluida para la Diáspora africana y trataré de recuperar la dimensión africana de ésta.

  7. Effect of domestic cooking on the starch digestibility, predicted glycemic indices, polyphenol contents and alpha amylase inhibitory properties of beans (Phaseolis vulgaris) and breadfruit (Treculia africana).

    Science.gov (United States)

    Chinedum, E; Sanni, S; Theressa, N; Ebere, A

    2018-01-01

    The effect of processing on starch digestibility, predicted glycemic indices (pGI), polyphenol contents and alpha amylase inhibitory properties of beans (Phaseolis vulgaris) and breadfruit (Treculia africana) was studied. Total starch ranged from 4.3 to 68.3g/100g, digestible starch ranged from 4.3 to 59.2 to 65.7g/100g for the raw and processed legumes; Resistance starch was not detected in most of the legumes except in fried breadfruit and the starches in both the raw and processed breadfruit were more rapidly digested than those from raw and cooked beans. Raw and processed breadfruit had higher hydrolysis curves than raw and processed beans with the amylolysis level in raw breadfruit close to that of white bread. Raw beans had a low glycemic index (GI); boiled beans and breadfruit had intermediate glycemic indices respectively while raw and fried breadfruit had high glycemic indices. Aqueous extracts of the food samples had weak α-amylase inhibition compared to acarbose. The raw and processed legumes contained considerable amounts of dietary phenols and flavonoids. The significant correlation (r=0.626) between α-amylase inhibitory actions of the legumes versus their total phenolic contents suggests the contribution of the phenolic compounds in these legumes to their α-amylase inhibitory properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Complexity, adaptations and variations in the secondary insemination system of female Dermanyssina mites (Acari: Anactinothrichida: Gamasida): the case of Afrocypholaelaps africana.

    Science.gov (United States)

    Di Palma, A; Seeman, O D; Alberti, G

    2017-07-01

    Gamasine mites, mainly of the taxon Dermanyssina, possess a secondarily evolved insemination system (sperm access system), of which there are two, generally recognized, structurally different types, the laelapid- and the phytoseiid-type. The ultrastructure of the female sperm access system in Afrocypholaelaps africana is described. It consists of paired insemination pores, opening between the bases of legs three and four, and paired cuticle-lined tubules that converge into a large, sack-like spermatheca, remarkably cuticle-lined as well. The entire spermatheca and part of the tubules are embedded in a peculiar syncytial tissue where numerous sperm cells are present. The general organization of this insemination system is of the laelapid-type. However, it presents striking structural differences, compared with the systems described in Varroa destructor and Hattena cometis, the other gamasine mites having a laelapid-type system studied ultrastructurally until now. The functional morphology, complexity and variations of the sperm access system in Dermanyssina are discussed and correlated with the evolutionary biology of the group.

  9. História e Cultura Afro-Brasileira e Africana na Educação Básica da Paraíba

    Directory of Open Access Journals (Sweden)

    Waldeci Ferreira Chagas

    2017-01-01

    Full Text Available Neste artigo discute-se sobre o ensino de história e cultura afro-brasileira e africana em escolas públicas da Paraíba. Nele analisam-se as experiências desenvolvidas por trinta docentes que atuam na educação básica e em escolas públicas municipais localizadas em cidades de três mesorregiões da Paraíba: litoral, agreste e brejo. Para a realização da análise, recorreu-se aos projetos desenvolvidos e executados pelos docentes, através dos quais foi discutido o conteúdo, a metodologia, os recursos didáticos e a relação entre a execução desses projetos e a efetivação da educação para as relações étnico-raciais.

  10. Relações comerciais e diplomáticas Anglo-africanas durante a expedição ao Níger de 1854

    Directory of Open Access Journals (Sweden)

    Alexsander Lemos de Almeida Gebara

    2016-08-01

    Full Text Available Resumo O artigo procura compreender a expedição britânica nos rios Niger e Benue em 1854 num contexto de transformação nas relações políticas e econômicas da Grã Bretanha com o interior da África Ocidental. Tal empreendimento ficou marcado pela ausência de mortes por febres tropicais e deixou vários registros, dentre eles relatos de viagem e a correspondência entre seus agentes e o Foreign Office e o Colonial Office que compõe o corpo de fontes deste artigo. Especial atenção é dedicada aos termos e formas das trocas comerciais realizadas com os africanos diretamente ao longo da viagem e às condições nas quais estes relacionamentos foram estabelecidos. Assim, procura-se por um lado, compreender a expedição como parte de um de um processo de ampliação da presença europeia no interior e, por outro lado, refletir sobre as estratégias africanas em diálogo com as transformações econômicas na bacia Atlântica em meados do século XIX.

  11. Benefits conferred by "timid" ants: active anti-herbivore protection of the rainforest tree Leonardoxa africana by the minute ant Petalomyrmex phylax.

    Science.gov (United States)

    Gaume, Laurence; McKey, Doyle; Anstett, Marie-Charlotte

    1997-10-01

    In this study, we demonstrate that an important benefit provided by the small host-specific ant Petalomyrmex phylax to its host plant Leonardoxa africana is efficient protection against herbivores. We estimate that in the absence of ants, insect herbivory would reduce the leaf area by about one-third. This contributes considerably to the fitness of the plant. Our estimates take into account not only direct damage, such as removal of leaf surface by chewing insects, but also the effects of sucking insects on leaf growth and expansion. Sucking insects are numerically predominant in this system, and the hitherto cryptic effects of ant protection against the growth-reducing effects of sucking insects accounted for half of the total estimated benefit of ant protection. We propose that the small size of workers confers a distinct advantage in this system. Assuming that resource limitation implies a trade off between size and number of ants, and given the small size of phytophagous insects that attack Leonardoxa, we conclude that fine-grained patrolling by a large number of small workers maximises protection of young leaves of this plant. Since herbivores are small and must complete their development on the young leaves of Leonardoxa, and since a high patrolling density is required for a fine-grained search for these enemies, numerous small ants should provide the most effective protection of young leaves of Leonardoxa. We also discuss other factors that may have influenced worker size in this ant.

  12. O dom e a iniciação revisitados: o dado e o feito em religiões de matriz africana no brasil

    Directory of Open Access Journals (Sweden)

    Marcio Goldman

    2012-08-01

    Full Text Available Partindo da conhecida oposição entre o que derivaria do "dom" e o que derivaria da "iniciação" nas religiões de matriz africana no Brasil, este trabalho visa, em um primeiro movimento, demonstrar etnograficamente que esse dualismo oculta um triadismo. O desdobramento da análise etnográfica levará, contudo e em seguida, à substituição desse triadismo por um modelo simultaneamente unitário e múltiplo. Neste, a "participação", em seus múltiplos sentidos, deverá ter um lugar ao lado do "dom" e da "iniciação", e as três categorias deverão ser entendidas como atualizações de um princípio subjacente único.Beginning with the known opposition between that which derives from the "gift" and that which derives from "initiation" in African-oriented religions in Brazil, this work aims to ethnographically demonstrate that said dualism actually conceals a triadism. The unfolding of ethnographic analysis in the article will, however, lead us to replace this triadism with a model that is simultaneously unified and multiple. In this, "participation" (in its multiple meanings should have a place next to the "gift" and "initiation" and the three categories should be construed as updates of a single under-lying principle.

  13. Effet du biotope sur la diversité floristique et le polymorphisme phénotypique des groupements à Tamarix africana Poir. dans les zones arides de la région de Khenchela (Est Algerien

    Directory of Open Access Journals (Sweden)

    Khabtane Abdelhamid

    2012-12-01

    Full Text Available RESUME Le genre Tamarix (Tamaricaceae regroupe plus de 80 espèces, parmi eux le Tamarix africana Poir. qui représente une très grande ubiquité en Algérie, soit du point de vue climatique (humidité et sécheresse, édaphique (sols salés et calcaires; où il représente l’espèce  à caractère typique des plantes thermo xérophytes. Pour contribuer à la connaissance de cette espèce et de son comportement nous avons essayé de suivre le comportement  phytosociologique ainsi que sa variabilité morphologique (l’hauteur, le recouvrement basale, nombre des ramifications à la base.. dans trois biotopes, extrêmement différents du point de vue climatique et édaphique,  dans les zones steppiques arides de la région de Khenchela (Est Algérien et qui sont  choisis  selon un transect Nord - Sud. Les résultats révèlent que les groupements à Tamarix africana Poir. représentent une richesse floristique importante, qui se diffère d’un site à l’autre, avec un polymorphisme phénotypique adaptée aux conditions spécifiques à chacun des trois sites et qui lui permet d’être l’espèce à forme arbustive  la plus adaptée pour la réhabilitation des écosystèmes dégradés dans les zones de transitions Désert-NordMots clés Tamarix africana P. - ubiquité- thermo xérophytes-  régions arides- halophytes- polymorphisme phénotypique

  14. Seed Dispersal Potential of Asian Elephants

    DEFF Research Database (Denmark)

    Harich, Franziska K.; Treydte, Anna Christina; Ogutu, Joseph Ochieng

    2016-01-01

    Elephants, the largest terrestrial mega-herbivores, play an important ecological role in maintaining forest ecosystem diversity. While several plant species strongly rely on African elephants (Loxodonta africana; L. cyclotis) as seed dispersers, little is known about the dispersal potential of As...

  15. Why do elephants flap their ears? | Wright | African Zoology

    African Journals Online (AJOL)

    The blood flow in the ear of the African elephant Loxodonta africana was measured In anaesthetized animals using the dye dilution technique at the same time as the arterio-venous temperature difference. The calculated heat loss from the ear is shown to be a substantial proportion of the total metabolic heat-loss ...

  16. Comparing direct image and wavelet transform-based approaches to analysing remote sensing imagery for predicting wildlife distribution

    NARCIS (Netherlands)

    Murwira, A.; Skidmore, A.K.

    2010-01-01

    In this study we tested the ability to predict the probability of elephant (Loxodonta africana) presence in an agricultural landscape of Zimbabwe based on three methods of measuring the spatial heterogeneity in vegetation cover, where vegetation cover was measured using the Landsat Thematic Mapper

  17. A note on the presence of the Elephant Louse Haematomyzus elephantis piaget (Mallophaga: Rhynchophthirina in the Kruger National Park

    Directory of Open Access Journals (Sweden)

    L.E.O Braack

    1984-12-01

    Full Text Available First described in 1869, this rather unusual insect has been found to be a common ectoparasite on the Indian elephant (Elephas maximus, and has been collected in low numbers from the African elephant (Loxodonta africana in nearly all of sub-saharan Africa (Ledger 1979, The arthropod parasites of vertebrates in Africa south of the Sahara (Ethiopian Region Vol. IV.

  18. Managing African Elephant Populations: Act or let die

    NARCIS (Netherlands)

    Colenbrander, Ben; Gooijer, Jean de; Paling, Robert; Stout, Susanna; Stout, Tom; Allen, Twink

    2004-01-01

    During the last century, the number of African elephant (Loxodonta africana) declined dramatically as a result of over-hunting, poaching for ivory and, more recently, the loss of habitat area due to encroachment of the human population. In some areas, however, the trend to declining numbers was

  19. 78 FR 9725 - Endangered Species; Receipt of Applications for Permit

    Science.gov (United States)

    2013-02-11

    ...-66682A The applicant requests a permit to re-export a captive-born male Asian elephant (Elephas maximus... species (Mescocapromys species), African elephant (Loxodonta Africana), Asian elephant (Elephas maximus... covers activities to be conducted by the applicant over a 5-year period Applicant: Hawthorn Corporation...

  20. 78 FR 50083 - Endangered Species; Marine Mammals; Receipt of Applications for Permit

    Science.gov (United States)

    2013-08-16

    ... a 5-year period. Applicant: Zoological Society of San Diego, San Diego, CA; PRT-08827B The applicant requests a permit to re-import a live female African elephant (Loxodonta africana) born in the wild for the... conducted by the applicant over a 5-year period. Applicant: Pinto Ranch, Hunt, TX; PRT-13263B The applicant...

  1. Pedagogias do corpo na educação da dança de matriz africana em Salvador, BA, Brasil: perspectivas e tensões do projeto emancipatório

    OpenAIRE

    Echeverry Zambrano, Claudia Del Pilar

    2013-01-01

    212 f. Esta tese, resultado de uma pesquisa de caráter etnográfico e bibliográfico, analisa as pedagogias usadas na educação do corpo, dentro da proposta das danças de matriz africana, que são praticadas em ambientes escolares em Salvador, Bahia, Brasil. O estudo faz uma ênfase na descrição das perspectivas e desafios que esta educação enfrenta na atualidade como projeto corporal emancipador e reestruturador das representações sobre o corpo negro, historicamente configuradas no marco moder...

  2. Control Químico de la Mosca de los Establos, Stomoxys Calcitrans (L y Otros Insectos Asociados con Estipes de Palma Africana en Descomposición

    Directory of Open Access Journals (Sweden)

    Ureta Sandino Eduardo

    1972-12-01

    Full Text Available En ensayos para determinar el efecto del diazinon 1% I.A. (ingrediente activo; bromophos 1 % I.A.; dieldrin 0.5% I.A., 2% I.A. y methomyl 0.1 % I.A. sobre larvas de Stomoxys calcilrans y otros insectos asociados con tipes de palma africana (Elaeis guineensis en descomposición, se encontró que los tratamientos con diazinon 1% I.A. y bromophos 1% I.A. fueron los más efectivos para impedir la proliferación en éstos de las larvas de Slomoxys calcilralls. Ambos insecticidas protegieron eficientemente los estipes por lo menos durante dos semanas. El dieldrin al 0.5% I. A. y 2% I. A., aunque inferior al bromophos 1% I.A. y al diazinon 1% I.A. también fue efectivo para impedir la proliferación de larvas de la mosca en los troncos de palma africana en descomposición. El tratamiento con methomyl 0.1 % I. A. al parecer no impidió la multiplicación de las larvas en los estipes, según pudo observarse en muestras tomadas a las dos semanas de haber sido aplicado el producto. El diazinon 1% I.A: bromophos 1 % I.A.; dieldrin 0.5% I.A. y 2% I.A., aparentemente fueron eficaces para controlar los adultos de Limnobaris calandriformis y Metamasius hemipterus, los cuales eran atraídos en grandes cantidades a los trozos de tallo de palma recién rajada, así como también impidieron la proliferación en éstos de las larvas de los dípteros Ormidea obesa y Hermelia sp./Abstract Several tests were carried out to determine the effectiveness of diazinon 1% I.A., bromophos 1% I.A., dieldrin 0.5 and 2% I.A., and methomyl 0.1 % on larvae of the stable fly, Stomoxys calcitrans, and other insects associated with dead trunks of the oil palm (Elaeis guineesis.The results showed by the author indicate that diazinon and bromophos were the most effective materials tested. Both insecticides protected well the dead trunks for at least two weeks. Dieldrin (both doses although less efficient than diazinon, was also effective in preventing the development of great numbers of

  3. Antimicrobial activity and probable mechanisms of action of medicinal plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus.

    Directory of Open Access Journals (Sweden)

    Peter G Mwitari

    Full Text Available Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 µl of the test extract (100 mg/ml were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 µg and fluconazole (25 µg were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78-100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC50200 µg/ml. Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to isolate and characterize the bioactive constituents continue.

  4. Evaluación agronómica y nutricional del pasto EStrella africana (Cynodon nlemfuensis en la zona de monteverde, puntarenas, Costa Rica. I. DISPONIBILIDAD DE BIOMASA Y FENOLOGÍA

    Directory of Open Access Journals (Sweden)

    Luis Villalobos

    2013-01-01

    Full Text Available Se evaluó la disponibilidad de biomasa y la fenología del pasto estrella africana (Cynodon nlemfuensis a lo largo de 2 años en muestreos bimensuales, en 4 fincas comerciales de ganado lechero ubicadas en los cantones de Tilarán y Central (latitud 10°20’ N, longitud 84°50’ O,altitud 800 a 1200 msnm de las provincias de Guanacaste y Puntarenas, respectivamente. La disponibilidad de materia seca pre-pastoreo y laedad fenológica promedio fueron 4484 kg.ha-1. corte-1 y 7,36 hojas verdes por rebrote, respec- tivamente. La composición botánica promediode las pasturas fue 86,81% estrella, 2,52% otrasgramíneas, 1,39% leguminosas, 1,53% malezas y 7,75% material senescente. La disponibilidad de biomasa fue mayor en las fincas con influencia climática del Oceano Pacífico y su producción disminuyó en los meses de mayor precipitación. La edad fenológica del pasto estrella africana se ubica entre 6 y 8 hojas verdes por rebrote, lo cual permite una adecuada recuperación del pasto, y disminuyó en los meses con excesos deprecipitación.

  5. La literatura autobiográfica africana escrita por mujeres: contratos de lectura. The African autobiographical literature written by women: reading contracts

    Directory of Open Access Journals (Sweden)

    Elena Cuasante

    2014-11-01

    Full Text Available El presente trabajo parte de la idea de que el estudio de los géneros literarios exige considerar no solo los rasgos formales del texto, sino también las diferentes modalidades contractuales susceptibles de aparecer en su recepción. Dicho de otro modo, un texto solo se integra en un género de escritura concreto cuando es reconocido como tal por parte del destinatario, operación que, aunque comporta ciertos conocimientos teóricos, es de carácter pragmático. El lector será quien, de manera individual, y apoyándose en todos los datos que tiene a su alcance, decida el modo de lectura que le resulta más apropiado. En este trabajo intentaremos ilustrar este proceso analizando un corpus de textos autobiográficos pertenecientes a la primera generación de escritoras africanas de expresión francesa, elección que pretende satisfacer al mismo tiempo los criterios de cohesión (todas las escritoras comparten un mismo contexto socio-histórico y de representatividad, pues pensamos que nuestras conclusiones son trasladables a otros corpus similares, en particular a los que se derivan de las denominadas “literaturas emergentes”. This paper is based on the idea that the study of literary genres needs to take into consideration not only the formal features of the text but also the different contractual modalities which might appear in their reception. In other words, a text is only part of a specific writing genre when it is recognized as such by the addressee, operation which, although entailing certain theoretical knowledge, has a pragmatic character. It will be the reader who, individually and relying on all the data at his disposal, will decide the reading process which he finds more appropriate. In this paper we will try to show this process by analysing a corpus of autobiographical texts written by the first generation of African French-speaking female writers, a choice which aims to meet at the same time the criteria of cohesion (all the

  6. Electronics and electronic systems

    CERN Document Server

    Olsen, George H

    1987-01-01

    Electronics and Electronic Systems explores the significant developments in the field of electronics and electronic devices. This book is organized into three parts encompassing 11 chapters that discuss the fundamental circuit theory and the principles of analog and digital electronics. This book deals first with the passive components of electronic systems, such as resistors, capacitors, and inductors. These topics are followed by a discussion on the analysis of electronic circuits, which involves three ways, namely, the actual circuit, graphical techniques, and rule of thumb. The remaining p

  7. CARBÓN ACTIVADO: EFECTO DEL LAVADO CON ÁCIDO SULFÚRICO DEL PRECURSOR LIGNOCELULÓSICO, CUESCO DE PALMA AFRICANA, SOBRE LOS PROCESOS DE CARBONIZACIÓN Y ACTIVACIÓN.

    Directory of Open Access Journals (Sweden)

    Luisa Fernanda Navarrete

    2008-03-01

    Full Text Available Se realizan lavados controlados durante diferentes periodos de tiempo, 6 y 12 horas, con soluciones diluidas de ácido sulfúrico, 2, 5 y 10%, sobre el precursor lignocelulósico cuesco de palma africana, consiguiendo reducir en más del 50% el contenido de cenizas de dicho material, en las que los componentes inorgánicos, principalmente elementos como hierro y aluminio, influyen notablemente en lareacción de gasificación con CO2 durante la activación física.Se determinan las entalpías de inmersión en las muestras con mayor grado de activación con resultados que se encuentran entre el 2 y 10 J.g-1, y se comparan con los obtenidos para carbones activados resultantes de lavar el material de partida con agua en los mismos períodos de tiempo.

  8. Caracterización estructural por adsorción y difracción de rayos X de monolitos de carbón activado a partir de cáscara de coco y cuesco de palma africana

    OpenAIRE

    Vargas Delgadillo, Diana; Giraldo-Gutiérrez, Liliana; Moreno-Piraján, Juan

    2009-01-01

    Se prepararon monolitos de carbón activado tipo disco utilizando como precursores por separado cáscara de coco y cuesco de palma africana mediante la activación química con ácido fosfórico, utilizando diferentes concentraciones, sin el uso de ningún aglomerante. Se presentan el rendimiento del proceso, así como los parámetros estructurales determinados por adsorción de N2 a 77 K y CO2 a 273 K, y se comparan con algunos parámetros cristalográficos determinados por difracción de rayos X. Se obt...

  9. A cidade africana contemporânea de origem portuguesa: São Tomé pré e pós-independência The contemporary African city of Portuguese origin: Sao Tome pre and post-independence

    Directory of Open Access Journals (Sweden)

    Teresa Madeira da Silva

    2012-12-01

    Full Text Available A cidade de São Tomé foi território português desde as primeiras ocupações até 1975 (data de sua independência,tendo, nesse tempo, crescido segundo os princípios do urbanismo de origem portuguesa. Para além da cidade planeada e consolidada, construída no período de ocupação colonial, a cidade desenvolveu, sobretudo no período pós-independência, um outro tipo de estrutura sem planeamento. À semelhança de outras cidades africanas de origem portuguesa, essa nova estrutura localiza-se na periferia do centro urbano. Este artigo apresenta dois argumentos. O primeiro considera que a cidade de São Tomé apresenta uma estrutura dual, tal como outras cidades africanas: uma zona central planeada, construída no período da ocupação colonial (pré-independência, e outra, periurbana, constituída essencialmente por habitações resultantes da expansão habitacional do centro urbano e com certas características semirrurais: vivendas associadas a espaços de produção agrícola familiar. O segundo argumento refere que tanto a estrutura central planeada, desenvolvida no período colonial, como a estrutura periférica não planeada, desenvolvida posteriormente,têm, na sua origem e desenvolvimento, a procura de relações com o território e, tanto numa como noutra,reconhecem-se estruturas urbanas adaptadas às condições locais.

  10. Producción de biomasa y costos de producción de pastos estrella africana (Cynodon nlemfuensis, kikuyo (Kikuyuocloa clandestina y ryegrass perenne (Lolium perenne en lecherías de Costa Rica

    Directory of Open Access Journals (Sweden)

    Luis Villalobos

    2013-01-01

    Full Text Available Se evaluó la producción de biomasa, los costos de producción y el costo del kilogramo de materia seca en los pastos kikuyo (Kikuyuocloa clandestina, ryegrass perenne (Lolium perenne y estrella africana (Cynodon nlemfuensis, a lo largo de un año, en 8 fincas comerciales ubicadas en las provincias de Cartago (2, San José (2 y Alajuela (4. La producción de biomasa promedio por ciclo para los 3 pastos fue de 3395 kg.ha-1 MS; la producción anual se ve influenciada por los días de recuperación de cada especie, mostrando valores de 40 170, 38 731 y 28 995 kg.ha-1 de MS para los pastos estrella africana, kikuyo y ryegrass perenne, respectivamente. La producción de biomasa varía durante el año y en las épocas de mayor producción de esa biomasa, los animales tienen un menor aprovechamiento de la pastura en términos porcentuales, debido a que la carga animal, los períodos de permanencia y las áreas de pastoreo no se ajustan a la disponibilidad de forraje. Los costos anuales de mano de obra, insumos y tierra promedio fueron de 72.433, 505.515 y 18.760 colones.ha-1, respectiva- mente; siendo los insumos el rubro con un peso relativo mayor en la estructura de costos de las fincas en pastoreo. Los costos del kg de MS producido y consumido, para los 3 pastos evaluados, fueron de 16,6 y 44,4 colones respectivamente, siendo el aprovechamiento que los animales hacen de las pasturas el determinante del costo del material consumido. Las fincas con mayor inversión anual en pasturas, mostraron un mayor retorno en kg.ha-1 leche.

  11. El proyecto político afroperuano: ¿La reivindicación de una diáspora africana sin África?; O projeto político afro-peruano: A reivindicação de uma diáspora africana sem África?; The Afro-Peruvian Political Project: The claim of an African diaspora without Africa?

    Directory of Open Access Journals (Sweden)

    Juan Enrique Pozada Pineda

    2015-07-01

    Full Text Available Resumen: Cuando nos referimos a los términos “diáspora africana”, “afrodescendencia” o “afrodescendientes”, inevitablemente debemos hacer referencia a África. En función a ello, África, podría entenderse como la raíz y el origen de estas tres dimensiones identitarias. En el caso del Perú, específicamente con el proyecto político étnico enarbolado por las organizaciones de derechos civiles afroperuanas y por algunas entidades del Estado especializadas en “lo afroperuano”, las reivindicaciones de una afrodescendencia o pertenencia a una diáspora africana, no suelen dirigirse a África, sino a sus pares afrodescendientes más próximos. Esto como si el Océano Atlántico fuese un gran abismo entre dos mundos muy distintos: el afrodescendiente y el africano. El presente trabajo pretende dar un acercamiento a esta realidad, en donde las luchas por la reivindicación de una diáspora africana se presentan sin África, sin lo africano, desarraigadas de su raíz, aunque sí, con un “África” imaginada, más “cercana” y menos “extraña”.   Palabras clave: Afroperuanos, diáspora, africanidades, proyectos identitarios, afrodescendencia.       Resumo: Quando nos referimos     aos termos "diáspora africana", "afrodescendência" ou "afrodescendentes", inevitavelmente devemos fazer referência à África. Em função disso, se podia entender a África como a raiz e origem destas três dimensões identitárias. No caso do Perú, especificamente com o projeto étnico-político elaborado pelas organizações de direitos civis afro- peruanas e por algumas entidades do Estado especializadas no "afroperuano", as reivindicações de uma afrodescendência ou pertença a uma diáspora africana, normalmente não para dirigir-se a África, se não a seus pares afrodescendentes     mais próximos. Isto como se o oceano Atlântico fosse um grande abismo entre dois mundos distintos: o do afrodescendente e o do africano. O

  12. Representações da História e cultura Afro-Brasileira e Africana nos documentos escolares de uma escola de Ensino Fundamental do Paraná

    Directory of Open Access Journals (Sweden)

    Sandra Aparecida Batista

    2017-05-01

    Full Text Available Diante da grande diversidade étnico-racial e dos conflitos e tensões em torno das representações da História e Cultura Afro-Brasileira e africana, o objeto de estudo desta pesquisa são as representações que se refletem nos documentos escolares, Projeto Político Pedagógico (PPP, Proposta Pedagógica Curricular (PPC e Plano de Trabalho Docente (PTD que sistematizam a organização didática pedagógica de uma escola do Ensino Fundamental do estado do Paraná. Partimos de algumas indagações que são discutidas ao longo do texto, a saber: o que são representações, conteúdos da disciplina de História isentos ou repletos de representações, e por fim a análise dos documentos escolares e dos respectivos conteúdos da disciplina de História referente às Séries Finais do Ensino Fundamental, considerando que os mesmos são permeados de representações. O estudo aponta que as representações denominadas de hegemônicas, advindas da classe dominante branca com um discurso preconceituoso e estereotipado foram sendo substituídas por representações anti-hegemônicas, que versam sobre o reconhecimento e valorização da História e Cultura Afro-Brasileira e Africana, tendo a Lei 10 639/03 um papel importante neste sentido. Por sua vez, alerta que não se trata de uma perspectiva homogeneizadora e uniformizadora, ou de transição curricular do protagonismo branco e europeu para o negro e africano, mas de uma visão plural, dinâmica e contextualizada da temática.

  13. Electronic technology

    International Nuclear Information System (INIS)

    Kim, Jin Su

    2010-07-01

    This book is composed of five chapters, which introduces electronic technology about understanding of electronic, electronic component, radio, electronic application, communication technology, semiconductor on its basic, free electron and hole, intrinsic semiconductor and semiconductor element, Diode such as PN junction diode, characteristic of junction diode, rectifier circuit and smoothing circuit, transistor on structure of transistor, characteristic of transistor and common emitter circuit, electronic application about electronic equipment, communication technology and education, robot technology and high electronic technology.

  14. Controle químico da "ERGOT" (Claviceps africana Frederickson, Mantle & de Milliano ou doença-açucarada e das principais doenças foliares do sorgo (Sorghum bicolor (L. Moench Chemical control of "ERGOT"(Claviceps africana Frederickson, Mantle & de Milliano or sugary disease and the main foliar diseases of sorghum (Sorghum bicolor (L. Moench

    Directory of Open Access Journals (Sweden)

    Nicésio Filadelfo Janssen de Almeida Pinto

    2003-08-01

    Full Text Available O controle químico da "ergot" (Claviceps africana foi realizado em campo de produção de sementes do híbrido de sorgo granífero BR 304 (Sorghum bicolor (L. Moench., utilizando-se os fungicidas (g i.a./ha: captan (1250,0, fenarimol (80,0, trifenil hidróxido de estanho (166,7, prochloraz (450,0, chlorothalonil (1500,0, iprodione (750,0, azoxystrobin (150,0, thiabendazole (360,0, procimidone (750,0, ziram (1500,0 e tebuconazole (200,0. Parcelas sem aplicação de fungicida constituíram a testemunha. As pulverizações foram realizadas com pulverizador costal manual, com o jato dirigido para as panículas. O intervalo das aplicações dos fungicidas foi de 4 dias, a partir da antese. Aos 7 dias após o término das pulverizações, a porcentagem de panículas doentes variou 5,4 para o fungicida tebuconazole e 100,0% para a maioria dos demais tratamentos. Para a porcentagem de flores doentes por panícula, os valores variaram de 0,3% a 65,0% para o fungicida tebuconazole e testemunha, respectivamente. Não ocorreu diferença significativa entre as porcentagens de flores doentes por panículas nos tratamentos tebuconazole (0,3%, chlorothalonil (2,5% e prochloraz (3,0%, sendo esses os mais eficientes no controle da ergot. Adicionalmente, o fungicida mais eficiente no controle da antracnose foliar (Colletotrichum graminicola foi o prochloraz, ao passo que para a ferrugem (Puccinia purpurea e a cercosporiose (Cercospora fusimaculans, o maior controle foi obtido com o fungicida tebuconazole. Não houve aumento da germinação das sementes em nenhum dos tratamentos; entretanto, o aumento do peso de mil sementes foi significativo para os tratamentos com os fungicidas prochloraz, chlorotalonil e tebuconazole.The efficiency of fungicides in the control of sugar disease of sorghum (Sorghum bicolor (L. Moench. was evaluated in a seed production field of the sorghum hybrid BR 304. The following fungicides and doses (g a.i./ha were evaluated : captan (1250

  15. The Electron

    Energy Technology Data Exchange (ETDEWEB)

    Thomson, George

    1972-01-01

    Electrons are elementary particles of atoms that revolve around and outside the nucleus and have a negative charge. This booklet discusses how electrons relate to electricity, some applications of electrons, electrons as waves, electrons in atoms and solids, the electron microscope, among other things.

  16. Hard electronics; Hard electronics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Hard material technologies were surveyed to establish the hard electronic technology which offers superior characteristics under hard operational or environmental conditions as compared with conventional Si devices. The following technologies were separately surveyed: (1) The device and integration technologies of wide gap hard semiconductors such as SiC, diamond and nitride, (2) The technology of hard semiconductor devices for vacuum micro- electronics technology, and (3) The technology of hard new material devices for oxides. The formation technology of oxide thin films made remarkable progress after discovery of oxide superconductor materials, resulting in development of an atomic layer growth method and mist deposition method. This leading research is expected to solve such issues difficult to be easily realized by current Si technology as high-power, high-frequency and low-loss devices in power electronics, high temperature-proof and radiation-proof devices in ultimate electronics, and high-speed and dense- integrated devices in information electronics. 432 refs., 136 figs., 15 tabs.

  17. Estimating variation in stomatal frequency at intra-individual, intra-site, and inter-taxonomic levels in populations of the Leonardoxa africana (Fabaceae) complex over environmental gradients in Cameroon

    Science.gov (United States)

    Finsinger, Walter; Dos Santos, Thibaut; McKey, Doyle

    2013-07-01

    Variation of stomatal frequency (stomatal density and stomatal index) includes genetically-based, potentially-adaptive variation, and variation due to phenotypic plasticity, the degree of which may be fundamental to the ability to maintain high water-use efficiency and thus to deal with environmental change. We analysed stomatal frequency and morphology (pore length, pore width) in leaves from several individuals from nine populations of four sub-species of the Leonardoxa africana complex. The dataset represents a hierarchical sampling wherein factors are nested within each level (leaves in individuals, individuals in sites, etc.), allowing estimation of the contribution of different levels to overall variation, using variance-component analysis. SI showed significant variation among sites ("site" is largely confounded with "sub-species"), being highest in the sub-species localized in the highest-elevation site. However, most of the observed variance was accounted for at intra-site and intra-individual levels. This variance could reflect great phenotypic plasticity, presumably in response to highly local variation in micro-environmental conditions.

  18. Telling Tales of War to Teens: Ignacio Martínez de Pisón's Una guerra africana and Morocco as "Open Wound" in the Spanish National Imaginary

    Directory of Open Access Journals (Sweden)

    Silvia Bermúdez

    2006-01-01

    Full Text Available Exactly ten years after its traumatic defeat in the Spanish-American War of 1898, Spain appeared to find some compensation for the loss of its last colonies by undertaking the invasion of Morocco in 1908. The enterprise proved difficult when the forces of Abd-el-Krim defeated the Spanish army in the summer of 1921. This terrible loss was metaphorized as an "open wound" and entered the collective imagination by becoming a theme in novels such as José Díaz Fernández's El blocao (1928, Ramón Sender's Imán (1930, and Arturo Barea's series La forja de un rebelde (1941-1944. Known as the "Disaster of Annual," the defeat appeared to be almost forgotten until a series of narratives in the late twentieth and early twenty-first centuries obsessively returned to this particular moment of Spanish history. I focus on how one such narrative, Martínez de Pisón's Una guerra africana (2000, revisits this war as adolescent literature ("novelas juveniles" and within the literary genre of the "novels of the War in Africa," and by so doing, contributes to the articulation of a Spanish collective identity with the historical memory of the feared Moroccan Other.

  19. In Vitro Antibacterial Potential of Extracts of Sterculia africana, Acacia sieberiana, and Cassia abbreviata ssp. abbreviata Used by Yellow Baboons (Papio cynocephalus for Possible Self-Medication in Mikumi National Park, Tanzania

    Directory of Open Access Journals (Sweden)

    Irene Kirabo

    2018-01-01

    Full Text Available The animals in general and nonhuman primates in particular self-medication has been widely reported; however, little is still known about the pharmacological activity of the extracts present in their daily diet. The in vitro antibacterial activity of the stem, root bark, and leaf extracts of three selected plants on which yellow baboons feed in unusual manner in Mikumi National Park, Tanzania, was evaluated. Crude plant extracts were tested against Gram positive and Gram negative bacteria of medical and veterinary importance employing a modified agar well diffusion method and Minimum Inhibitory Concentration (MIC technique. The lowest MIC value for Gram positive strains was 0.31 mg/ml demonstrated by Cassia abbreviata ssp. abbreviata against Staphylococcus aureus (ATCC 25923. The highest susceptibility to the ethanol plant extracts was exhibited by Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, examples of microbes that affect both human and nonhuman primates. These findings demonstrate that the plant extracts from Sterculia africana, Acacia sieberiana, and Cassia abbreviata ssp. abbreviata have antibacterial activity and may be used as feed for their prophylactic benefits. Remarkably, the lowest MIC of 0.16 mg/ml was only 16-fold weaker than Gentamicin, a standard drug.

  20. Electron radiography

    Science.gov (United States)

    Merrill, Frank E.; Morris, Christopher

    2005-05-17

    A system capable of performing radiography using a beam of electrons. Diffuser means receive a beam of electrons and diffuse the electrons before they enter first matching quadrupoles where the diffused electrons are focused prior to the diffused electrons entering an object. First imaging quadrupoles receive the focused diffused electrons after the focused diffused electrons have been scattered by the object for focusing the scattered electrons. Collimator means receive the scattered electrons and remove scattered electrons that have scattered to large angles. Second imaging quadrupoles receive the collimated scattered electrons and refocus the collimated scattered electrons and map the focused collimated scattered electrons to transverse locations on an image plane representative of the electrons' positions in the object.

  1. Age group estimation in free-ranging African elephants based on acoustic cues of low-frequency rumbles

    OpenAIRE

    Stoeger, Angela S.; Zeppelzauer, Matthias; Baotic, Anton

    2014-01-01

    Animal vocal signals are increasingly used to monitor wildlife populations and to obtain estimates of species occurrence and abundance. In the future, acoustic monitoring should function not only to detect animals, but also to extract detailed information about populations by discriminating sexes, age groups, social or kin groups, and potentially individuals. Here we show that it is possible to estimate age groups of African elephants (Loxodonta africana) based on acoustic parameters extracte...

  2. Surgical treatment of an umbilical hernia in a free-ranging sub-adult African elephant in Samburu National Reserve, Kenya

    OpenAIRE

    Kaitho, Titus; Mijele,Dominic; Njoroge,Michael

    2015-01-01

    Domnic Mijele, Michael Njoroge, Titus Kaitho Veterinary Services Department, Species Conservation and Management Division, Kenya Wildlife Service, Nairobi, Kenya Abstract: A 10-year-old male African elephant (Loxodonta africana) at Samburu National Reserve in Northern Kenya, weighing approximately 1,600 kg, presented with an umbilical hernia in October 2013. Umbilical herniorrhaphy was carried out under field conditions. Anesthesia was induced and maintained using etorphine hydrochloride for...

  3. Electrons, Electronic Publishing, and Electronic Display.

    Science.gov (United States)

    Brownrigg, Edwin B.; Lynch, Clifford A.

    1985-01-01

    Provides a perspective on electronic publishing by distinguishing between "Newtonian" publishing and "quantum-mechanical" publishing. Highlights include media and publishing, works delivered through electronic media, electronic publishing and the printed word, management of intellectual property, and recent copyright-law issues…

  4. Electron detector

    International Nuclear Information System (INIS)

    Hashimoto, H.; Mogami, A.

    1975-01-01

    A device for measuring electron densities at a given energy level in an electron beam or the like having strong background noise, for example, in the detection of Auger electric energy spectrums is described. An electron analyzer passes electrons at the given energy level and at the same time electrons of at least one adjacent energy level. Detecting means associated therewith produce signals indicative of the densities of the electrons at each energy level and combine these signals to produce a signal indicative of the density of the electrons of the given energy level absent background noise

  5. Electron/electron acoustic instability

    International Nuclear Information System (INIS)

    Gary, S.P.

    1987-01-01

    The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

  6. Electronic emission and electron guns

    International Nuclear Information System (INIS)

    Roy, Amitava

    2010-01-01

    This paper reviews the process of electron emission from metal surface. Although electrons move freely in conductors like metals, they normally do not leave the metal without some manipulation. In fact, heating and bombardment are the two primary ways in which electrons are emitted through the use of a heating element behind the cathode (termed thermionic emission) or as a result of bombardment with a beam of electrons, ions, or metastable atoms (termed secondary emission). Another important emission mechanism called Explosive Electron Emission (EEE) is also often used in various High Voltage Pulse Power Systems to generate very high current (few hundreds of kA) pulsed electron beams. The electron gun is the device in that it shoots off a continuous (or pulsed) stream of electrons. A brief idea about the evolution of the electron gun components and their basis of functioning are also discussed. (author)

  7. Sticker electronics

    KAUST Repository

    Hussain, Muhammad Mustafa; Torres Sevilla, Galo Andres; Diaz Cordero, Marlon Steven

    2017-01-01

    Electronic stickers may be manufactured on flexible substrates (110, 120, 130) as layers and packaged together. The package may then have an adhesive applied to one side to provide capability for sticking the electronic devices to surfaces

  8. ELECTRONIC SIGNATURES

    African Journals Online (AJOL)

    10332324

    "[to] promote the understanding and, acceptance of and growth in the number of electronic transactions .... Chapter III of the ECT Act is based on the UNCITRAL Model Law on Electronic. Commerce ... Communications Technology Law 146. 22.

  9. Electronic components

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful

  10. Understand electronics

    CERN Document Server

    Bishop, Owen

    2013-01-01

    Understand Electronics provides a readable introduction to the exciting world of electronics for the student or enthusiast with little previous knowledge. The subject is treated with the minimum of mathematics and the book is extensively illustrated.This is an essential guide for the newcomer to electronics, and replaces the author's best-selling Beginner's Guide to Electronics.The step-by-step approach makes this book ideal for introductory courses such as the Intermediate GNVQ.

  11. Electronic Commerce

    OpenAIRE

    Slavko Đerić

    2016-01-01

    Electronic commerce can be defined in different ways. Any definition helps to understand and explain that concept as better as possible.. Electronic commerce is a set of procedures and technologies that automate the tasks of financial transactions using electronic means. Also, according to some authors, electronic commerce is defined as a new concept, which is being developed and which includes process of buying and selling or exchanging products, services or information via computer networks...

  12. Electronic Publishing.

    Science.gov (United States)

    Lancaster, F. W.

    1989-01-01

    Describes various stages involved in the applications of electronic media to the publishing industry. Highlights include computer typesetting, or photocomposition; machine-readable databases; the distribution of publications in electronic form; computer conferencing and electronic mail; collaborative authorship; hypertext; hypermedia publications;…

  13. Sticker electronics

    KAUST Repository

    Hussain, Muhammad Mustafa

    2017-09-08

    Electronic stickers may be manufactured on flexible substrates (110, 120, 130) as layers and packaged together. The package may then have an adhesive applied to one side to provide capability for sticking the electronic devices to surfaces. The stickers can be wrappable, placed on surfaces, glued on walls or mirrors or wood or stone, and have electronics (112, 122, 132) which may or may not be ultrathin. Packaging for the electronic sticker can use polymer on cellulose manufacturing and/or three dimensional (3-D) printing. The electronic stickers may provide lighting capability, sensing capability, and/or recharging capabilities.

  14. Basic electronics

    CERN Document Server

    Holbrook, Harold D

    1971-01-01

    Basic Electronics is an elementary text designed for basic instruction in electricity and electronics. It gives emphasis on electronic emission and the vacuum tube and shows transistor circuits in parallel with electron tube circuits. This book also demonstrates how the transistor merely replaces the tube, with proper change of circuit constants as required. Many problems are presented at the end of each chapter. This book is comprised of 17 chapters and opens with an overview of electron theory, followed by a discussion on resistance, inductance, and capacitance, along with their effects on t

  15. Electronic Commerce and Electronic Business

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    This special issue is motivated by the recent upsurge of research activity in the areas of electronic commerce and electronic business both in India and all over the world. The current ... Monte Carlo methods for pricing financial options are then.

  16. Electronic Government and Electronic Participation

    NARCIS (Netherlands)

    Tambouris, E; Scholl, H.J.; Janssen, M.F.W.H.A.; Wimmer, M.A.; Tarabanis, K; Gascó, M; Klievink, A.J.; Lindgren, I; Milano, M; Panagiotopoulos, P; Pardo, T.A.; Parycek, P; Sæbø, Ø

    2016-01-01

    Electronic government and electronic participation continue to transform the public sector and society worldwide and are constantly being transformed themselves by emerging information and communication technologies.This book presents papers from the 14th International Federation for Information

  17. Electronic Government and Electronic Participation

    NARCIS (Netherlands)

    Tambouris, E.; Scholl, H.J.; Janssen, M.F.W.H.A.; Wimmer, M.A.; Tarabanis, K.; Gascó, M.; Klievink, A.J.; Lindgren, I.; Milano, M.; Panagiotopoulos, P.; Pardo, T.A.; Parycek, P.; Sæbø, O.

    2015-01-01

    Electronic government and electronic participation continue to transform the public sector and society worldwide and are constantly being transformed themselves by emerging information and communication technologies. This book presents papers from the 14th International Federation for Information

  18. Electron Tree

    DEFF Research Database (Denmark)

    Appelt, Ane L; Rønde, Heidi S

    2013-01-01

    The photo shows a close-up of a Lichtenberg figure – popularly called an “electron tree” – produced in a cylinder of polymethyl methacrylate (PMMA). Electron trees are created by irradiating a suitable insulating material, in this case PMMA, with an intense high energy electron beam. Upon discharge......, during dielectric breakdown in the material, the electrons generate branching chains of fractures on leaving the PMMA, producing the tree pattern seen. To be able to create electron trees with a clinical linear accelerator, one needs to access the primary electron beam used for photon treatments. We...... appropriated a linac that was being decommissioned in our department and dismantled the head to circumvent the target and ion chambers. This is one of 24 electron trees produced before we had to stop the fun and allow the rest of the accelerator to be disassembled....

  19. `Twisted' electrons

    Science.gov (United States)

    Larocque, Hugo; Kaminer, Ido; Grillo, Vincenzo; Leuchs, Gerd; Padgett, Miles J.; Boyd, Robert W.; Segev, Mordechai; Karimi, Ebrahim

    2018-04-01

    Electrons have played a significant role in the development of many fields of physics during the last century. The interest surrounding them mostly involved their wave-like features prescribed by the quantum theory. In particular, these features correctly predict the behaviour of electrons in various physical systems including atoms, molecules, solid-state materials, and even in free space. Ten years ago, new breakthroughs were made, arising from the new ability to bestow orbital angular momentum (OAM) to the wave function of electrons. This quantity, in conjunction with the electron's charge, results in an additional magnetic property. Owing to these features, OAM-carrying, or twisted, electrons can effectively interact with magnetic fields in unprecedented ways and have motivated materials scientists to find new methods for generating twisted electrons and measuring their OAM content. Here, we provide an overview of such techniques along with an introduction to the exciting dynamics of twisted electrons.

  20. Traços da religiosidade africana no carnaval carioca (Traces of African religiosity in carioca carnival - DOI: 10.5752/P.2175-5841.2013v11n29p53

    Directory of Open Access Journals (Sweden)

    José Geraldo Rocha

    2013-03-01

    Full Text Available As discussões a respeito do sagrado na contemporaneidade têm ganhado relevância ao considerarmos as novas perspectivas que se abrem com a inclusão de alguns temas relativos à diversidade cultural e religiosa na sociedade brasileira. Cada dia é perceptível o crescente espaço que o sagrado ocupa na vida cotidiana das pessoas comuns. A presença do sagrado no cotidiano da cultura brasileira é uma marca que realça um relevante aspecto da identidade nacional. A cultura brasileira é uma cultura plural. Para além das matrizes indígenas e européias, existe uma grande variedade cultural no âmbito da africanidade. O presente artigo objetiva analisar como esse elemento sagrado de caráter afro-brasileiro aparece nos enredos das escolas de samba do Rio de Janeiro durante os carnavais de 2011 e 2012. Nosso referencial são as letras dos sambas-enredos das escolas dos grupos C, D, e E que desfilam na Intendente Magalhães, subúrbio do rio de Janeiro. Palavras-chave: Religiosidade. Africana. Sagrado. Carnaval. Rio de Janeiro. Abstract The discussions about the sacred in contemporaneity have gained importance in considering new opportunities opening up with the inclusion of issues related to cultural and religious diversity in Brazilian society. It is noticeable the growing space that sacred plays in everyday life of ordinary people. The presence of the sacred in everyday Brazilian culture is a mark that highlights an relevant aspect of national identity. Brazilian culture is a plural culture. In addition to the indigenous and European origin, there is a great cultural variety in the scope of Africanity. This article aims to analyze how this sacred element of Afro-Brazilian characteristic appears in plots of samba schools in Rio de Janeiro during the carnivals of 2011 and 2012. Our references are the lyrics of the samba schools’ plots of groups C, D, and E, which parade on Intendente Magalhães Street, in a suburban area of Rio de Janeiro. Key

  1. Valoración ecosistémica a partir del uso de métricas de paisaje aplicando sistemas de información geográfica en cultivos de palma africana

    Directory of Open Access Journals (Sweden)

    Claudia Mayelly Ramírez Cano

    2016-12-01

    Full Text Available La valoración del paisaje es una herramienta que contribuye en los procesos de gestión y planificación mediante la generación de indicadores que permiten caracterizar las condiciones del territorio. En esta investigación se analizaron las métricas de paisaje a partir de: área de la clase (CA, área total del paisaje (TA, porcentaje del área total del paisaje (PLAND, número de parches de la clase (NP y densidad de parches (PD, relación área-perímetro promedio (MPAR, índice de diversidad de Shannon (SDI e índice de equitatividad de Shannon  (SEI y la valoración se realizó con la adaptación metodológica de los autores Paula Másmela y Alejandro Gómez, dicha adaptación permitió discernir sobre las características y calidad del paisaje en el municipio de Puerto Wilches, Santander, Colombia, durante el periodo entre 1987 y 2015.  La valoración paisajística se realizó a partir de imágenes de satélite mediante análisis multitemporal de las coberturas para cuantificar y caracterizar las transformaciones paisajísticas dadas en el territorio. Los resultados obtenidos muestran que en el año 1987 el paisaje era más dinámico, constituido por variedad de coberturas y ecosistemas; mientras en 2015 existe una implementación a gran escala del monocultivo de palma africana que rompe con la estructura paisajística, sin embargo, el resultado de calidad visual arrojó clasificación media, que evidencia la importancia de realizar una revisión a fondo sobre las actuales políticas de ordenación del territorio.

  2. Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Slavko Đerić

    2016-12-01

    Full Text Available Electronic commerce can be defined in different ways. Any definition helps to understand and explain that concept as better as possible.. Electronic commerce is a set of procedures and technologies that automate the tasks of financial transactions using electronic means. Also, according to some authors, electronic commerce is defined as a new concept, which is being developed and which includes process of buying and selling or exchanging products, services or information via computer networks, including the Internet. Electronic commerce is not limited just to buying and selling, but it also includes all pre-sales and after-sales ongoing activities along the supply chain. Introducing electronic commerce, using the Internet and Web services in business, realizes the way to a completely new type of economy - internet economy.

  3. Advanced Electronics

    Science.gov (United States)

    2017-07-21

    AFRL-RV-PS- AFRL-RV-PS- TR-2017-0114 TR-2017-0114 ADVANCED ELECTRONICS Ashwani Sharma 21 Jul 2017 Interim Report APPROVED FOR PUBLIC RELEASE...NUMBER Advanced Electronics 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 62601F 6. AUTHOR(S) 5d. PROJECT NUMBER 4846 Ashwani Sharma 5e. TASK NUMBER...Approved for public release; distribution is unlimited. (RDMX-17-14919 dtd 20 Mar 2018) 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Space Electronics

  4. Electron spectroscopy

    International Nuclear Information System (INIS)

    Hegde, M.S.

    1979-01-01

    An introduction to the various techniques in electron spectroscopy is presented. These techniques include: (1) UV Photoelectron spectroscopy, (2) X-ray Photoelectron spectroscopy, (3) Auger electron spectroscopy, (4) Electron energy loss spectroscopy, (5) Penning ionization spectroscopy and (6) Ion neutralization spectroscopy. The radiations used in each technique, the basis of the technique and the special information obtained in structure determination in atoms and molecules by each technique are summarised. (A.K.)

  5. Polymer electronics

    CERN Document Server

    Hsin-Fei, Meng

    2013-01-01

    Polymer semiconductor is the only semiconductor that can be processed in solution. Electronics made by these flexible materials have many advantages such as large-area solution process, low cost, and high performance. Researchers and companies are increasingly dedicating time and money in polymer electronics. This book focuses on the fundamental materials and device physics of polymer electronics. It describes polymer light-emitting diodes, polymer field-effect transistors, organic vertical transistors, polymer solar cells, and many applications based on polymer electronics. The book also disc

  6. Electronics Industry

    National Research Council Canada - National Science Library

    Bell, Robert; Carroll-Garrison, Martina; Donovan, Daniel; Fisher, John; Guemmer, Paul; Harms, Robert; Kelly, Timothy; Love, Mattie; McReynolds, James; Ward, Ralph

    2006-01-01

    .... Government action to preserve strategic access to semiconductor producers is clearly needed to ensure DoD electronic systems can be built without compromising sensitive technology, though every...

  7. Microfluidic electronics.

    Science.gov (United States)

    Cheng, Shi; Wu, Zhigang

    2012-08-21

    Microfluidics, a field that has been well-established for several decades, has seen extensive applications in the areas of biology, chemistry, and medicine. However, it might be very hard to imagine how such soft microfluidic devices would be used in other areas, such as electronics, in which stiff, solid metals, insulators, and semiconductors have previously dominated. Very recently, things have radically changed. Taking advantage of native properties of microfluidics, advances in microfluidics-based electronics have shown great potential in numerous new appealing applications, e.g. bio-inspired devices, body-worn healthcare and medical sensing systems, and ergonomic units, in which conventional rigid, bulky electronics are facing insurmountable obstacles to fulfil the demand on comfortable user experience. Not only would the birth of microfluidic electronics contribute to both the microfluidics and electronics fields, but it may also shape the future of our daily life. Nevertheless, microfluidic electronics are still at a very early stage, and significant efforts in research and development are needed to advance this emerging field. The intention of this article is to review recent research outcomes in the field of microfluidic electronics, and address current technical challenges and issues. The outlook of future development in microfluidic electronic devices and systems, as well as new fabrication techniques, is also discussed. Moreover, the authors would like to inspire both the microfluidics and electronics communities to further exploit this newly-established field.

  8. Electron holography

    CERN Document Server

    Tonomura, Akira

    1993-01-01

    Holography was devised for breaking through the resolution limit of electron microscopes The advent of a "coherent" field emission electron beam has enabled the use of Electron Holography in various areas of magnetic domain structures observation, fluxon observation in superconductors, and fundamental experiments in physics which have been inaccessible using other techniques After examining the fundamentals of electron holography and its applications to the afore mentioned fields, a detailed discussion of the Aharonov-Bohm effect and the related experiments is presented Many photographs and illustrations are included to elucidate the text

  9. The electron

    International Nuclear Information System (INIS)

    Hestenes, David; Weingartshofer, Antonio

    1991-01-01

    The stupendous successes of the Dirac equation and quantum electro-dynamics have established the electron as the best understood of the fundamental constituents of matter. Nevertheless, physicists agree that the electron still has secrets to reveal. Moreover, powerful new theoretical and experimental tools for probing those secrets have been sharpened during the last decade. This workshop was organized to bring theorists and experimentalists together to discuss their common goal of knowing the electron. Present state and future prospects for progress toward that goal are here described. The theoretical papers encompass a wide range of views on the electron. Several argue that the 'Zitter-bewegung' is more than a mathematical peculiarity of the Dirac equation, that it may well be a real physical phenomenon and worthy of serious study, theoretically and experimentally. Besides generating the electron spin and magnetic moment, the 'Zitterbewegung' may be a vital clue to electron structure and self-interaction. Some of the papers employ a radical new formulation of the Dirac theory which reveals a hidden geo-metric structure in the theory that supports a 'Zitterbewegung' inter-pretation. For the last half century the properties of electrons have been probed primarily by scattering experiments at ever higher energies. Recently, however, two powerful new experimental techniques have emerged capable of giving alternative experimental views of the electron. First, techniques for confining single electrons for long term study have led to the most accurate measurements of the electron magnetic moment. Second, the interaction of high intensity laser fields with atoms and electrons have revealed striking new phenomena such as multiphoton ionization. refs.; figs.; tabs

  10. Printed Electronics

    Science.gov (United States)

    Korkut, Sibel (Inventor); Chiang, Katherine S. (Inventor); Crain, John M. (Inventor); Aksay, Ilhan A. (Inventor); Lettow, John S. (Inventor); Chen, Chuan-Hua (Inventor); Prud'Homme, Robert K. (Inventor)

    2018-01-01

    Printed electronic device comprising a substrate onto at least one surface of which has been applied a layer of an electrically conductive ink comprising functionalized graphene sheets and at least one binder. A method of preparing printed electronic devices is further disclosed.

  11. Digital electronics

    CERN Document Server

    Morris, John

    2013-01-01

    An essential companion to John C Morris's 'Analogue Electronics', this clear and accessible text is designed for electronics students, teachers and enthusiasts who already have a basic understanding of electronics, and who wish to develop their knowledge of digital techniques and applications. Employing a discovery-based approach, the author covers fundamental theory before going on to develop an appreciation of logic networks, integrated circuit applications and analogue-digital conversion. A section on digital fault finding and useful ic data sheets completes th

  12. Electronic diagrams

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Diagrams is a ready reference and general guide to systems and circuit planning and in the preparation of diagrams for both newcomers and the more experienced. This book presents guidelines and logical procedures that the reader can follow and then be equipped to tackle large complex diagrams by recognition of characteristic 'building blocks' or 'black boxes'. The goal is to break down many of the barriers that often seem to deter students and laymen in learning the art of electronics, especially when they take up electronics as a spare time occupation. This text is comprised of nin

  13. Polymer electronics

    CERN Document Server

    Geoghegan, Mark

    2013-01-01

    Polymer electronics is the science behind many important new developments in technology, such as the flexible electronic display (e-ink) and many new developments in transistor technology. Solar cells, light-emitting diodes, and transistors are all areas where plastic electronics is likely to, or is already having, a serious impact on our daily lives. With polymer transistors and light-emitting diodes now being commercialised, there is a clear need for a pedagogic text thatdiscusses the subject in a clear and concise fashion suitable for senior undergraduate and graduate students. The content

  14. Starting electronics

    CERN Document Server

    Brindley, Keith

    2005-01-01

    Starting Electronics is unrivalled as a highly practical introduction for hobbyists, students and technicians. Keith Brindley introduces readers to the functions of the main component types, their uses, and the basic principles of building and designing electronic circuits. Breadboard layouts make this very much a ready-to-run book for the experimenter; and the use of multimeter, but not oscilloscopes, puts this practical exploration of electronics within reach of every home enthusiast's pocket. The third edition has kept the simplicity and clarity of the original. New material

  15. Stretchable electronics

    CERN Document Server

    Someya, Takao

    2012-01-01

    With its comprehensive coverage this handbook and ready reference brings together some of the most outstanding scientists in the field to lay down the undisputed knowledge on how to make electronics stretchable.As such, it focuses on gathering and evaluating the materials, designs, models and technologies that enable the fabrication of fully elastic electronic devices which can sustain high strain. Furthermore, it provides a review of those specific applications that directly benefit from highly compliant electronics, including transistors, photonic devices and sensors. In addition to stre

  16. Electron optics

    CERN Document Server

    Grivet, Pierre; Bertein, F; Castaing, R; Gauzit, M; Septier, Albert L

    1972-01-01

    Electron Optics, Second English Edition, Part I: Optics is a 10-chapter book that begins by elucidating the fundamental features and basic techniques of electron optics, as well as the distribution of potential and field in electrostatic lenses. This book then explains the field distribution in magnetic lenses; the optical properties of electrostatic and magnetic lenses; and the similarities and differences between glass optics and electron optics. Subsequent chapters focus on lens defects; some electrostatic lenses and triode guns; and magnetic lens models. The strong focusing lenses and pris

  17. Electronic identity

    CERN Document Server

    de Andrade, Norberto Nuno Gomes; Argles, David

    2014-01-01

    With the increasing availability of electronic services, security and a reliable means by which identity is verified is essential.Written by Norberto Andrade the first chapter of this book provides an overview of the main legal and regulatory aspects regarding electronic identity in Europe and assesses the importance of electronic identity for administration (public), business (private) and, above all, citizens. It also highlights the role of eID as a key enabler of the economy.In the second chapter Lisha Chen-Wilson, David Argles, Michele Schiano di Zenise and Gary Wills discuss the user-cent

  18. Em torno das "Diretrizes curriculares nacionais para a educação das relações étnico-raciais e para o ensino de história e cultura afro-brasileira e africana": uma conversa com historiadores

    Directory of Open Access Journals (Sweden)

    Martha Abreu

    2008-06-01

    Full Text Available A partir do crescimento do interesse de professores e secretarias de educação na organização de políticas de combate ao racismo, este artigo procura discutir e apresentar alguns subsídios para a implementação das "Diretrizes curriculares nacionais para o ensino das relações étnico-raciais e de história e cultura afro-brasileira e africana", aprovadas em 2004. Entendemos as "Diretrizes" como uma importante estratégia pedagógica para levar à escola, pela primeira vez, a discussão das relações raciais no Brasil, tantas vezes silenciada ou desqualificada pelas avaliações de que o Brasil era uma democracia racial. Demos especial atenção aos limites e possibilidades de trabalho com os conceitos de cultura afro-brasileira e identidade negra.

  19. Power Electronics

    DEFF Research Database (Denmark)

    Iov, Florin; Ciobotaru, Mihai; Blaabjerg, Frede

    2008-01-01

    is to change the electrical power production sources from the conventional, fossil (and short term) based energy sources to renewable energy resources. The other is to use high efficient power electronics in power generation, power transmission/distribution and end-user application. This paper discuss the most...... emerging renewable energy sources, wind energy, which by means of power electronics are changing from being a minor energy source to be acting as an important power source in the energy system. Power electronics is the enabling technology and the presentation will cover the development in wind turbine...... technology from kW to MW, discuss which power electronic solutions are most feasible and used today....

  20. Paper electronics.

    Science.gov (United States)

    Tobjörk, Daniel; Österbacka, Ronald

    2011-05-03

    Paper is ubiquitous in everyday life and a truly low-cost substrate. The use of paper substrates could be extended even further, if electronic applications would be applied next to or below the printed graphics. However, applying electronics on paper is challenging. The paper surface is not only very rough compared to plastics, but is also porous. While this is detrimental for most electronic devices manufactured directly onto paper substrates, there are also approaches that are compatible with the rough and absorptive paper surface. In this review, recent advances and possibilities of these approaches are evaluated and the limitations of paper electronics are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Electron Microprobe

    Data.gov (United States)

    Federal Laboratory Consortium — The JEOL JXA-8600 is a conventional hairpin filament thermal emission electron microprobe that is more than 20 years old. It is capable of performing qualitative and...

  2. Electronic Aggression

    Centers for Disease Control (CDC) Podcasts

    Aggression is no longer limited to the school yard. New forms of electronic media, such as blogs, instant messaging, chat rooms, email, text messaging, and the internet are providing new arenas for youth violence to occur.

  3. Electron Emitters

    National Research Council Canada - National Science Library

    Tzeng, Yonhua

    2002-01-01

    When two carbon-nanotube coated electrodes are placed at a small distance from each other, electron emission from carbon nanotubes allows a DC or AC electrical current to flow between these two electrodes...

  4. Electronic plants

    Science.gov (United States)

    Stavrinidou, Eleni; Gabrielsson, Roger; Gomez, Eliot; Crispin, Xavier; Nilsson, Ove; Simon, Daniel T.; Berggren, Magnus

    2015-01-01

    The roots, stems, leaves, and vascular circuitry of higher plants are responsible for conveying the chemical signals that regulate growth and functions. From a certain perspective, these features are analogous to the contacts, interconnections, devices, and wires of discrete and integrated electronic circuits. Although many attempts have been made to augment plant function with electroactive materials, plants’ “circuitry” has never been directly merged with electronics. We report analog and digital organic electronic circuits and devices manufactured in living plants. The four key components of a circuit have been achieved using the xylem, leaves, veins, and signals of the plant as the template and integral part of the circuit elements and functions. With integrated and distributed electronics in plants, one can envisage a range of applications including precision recording and regulation of physiology, energy harvesting from photosynthesis, and alternatives to genetic modification for plant optimization. PMID:26702448

  5. Electronic Elections

    DEFF Research Database (Denmark)

    Schürmann, Carsten

    2009-01-01

    Electronic voting technology is a two edged sword. It comes with many risks but brings also many benefits. Instead of flat out rejecting the technology as uncontrollably dangerous, we advocate in this paper a different technological angle that renders electronic elections trustworthy beyond...... the usual levels of doubt. We exploit the trust that voters currently have into the democratic process and model our techniques around that observation accordingly. In particular, we propose a technique of trace emitting computations to record the individual steps of an electronic voting machine...... for a posteriori validation on an acceptably small trusted computing base. Our technology enables us to prove that an electronic elections preserves the voter’s intent, assuming that the voting machine and the trace verifier are independent....

  6. Electronic commerce

    OpenAIRE

    Zvolánková, Pavla

    2010-01-01

    The thesis deals with a description of electronic commerce from its beginning up to present situation in this area. It explains basic terms connected with electronic commerce and it summarizes the relevant legislation. Moreover it describes e-contracts and rights and duties of both contractual parties. The main view is the view of Internet retailer, which is reflected in the practical part focused on concrete problems of retailers.

  7. Printed Electronics

    Science.gov (United States)

    Wade, Jessica; Hollis, Joseph Razzell; Wood, Sebastian

    2018-04-01

    The combination of printing technology with manufacturing electronic devices enables a new paradigm of printable electronics, where 'smart' functionality can be readily incorporated into almost any product at low cost. Over recent decades, rapid progress has been made in this field, which is now emerging into the industrial andcommercial realm. However, successful development and commercialisation on a large scale presents some significant technical challenges. For fully-printable electronic systems, all the component parts must be deposited from solutions (inks), requiring the development of new inorganic, organic and hybrid materials.A variety of traditional printing techniques are being explored and adapted forprinting these new materials in ways that result in the best performing electronicdevices. Whilst printed electronics research has initially focused on traditional typesof electronic device such as light-emitting diodes, transistors, and photovoltaics, it is increasingly apparent that a much wider range of applications can be realised. The soft and stretchable nature of printable materials makes them perfect candidates forbioelectronics, resulting in a wealth of research looking at biocompatible printable inks and biosensors. Regardless of application, the properties of printed electronicmaterials depend on the chemical structures, processing conditions, device architecture,and operational conditions, the complex inter-relationships of which aredriving ongoing research. We focus on three particular 'hot topics', where attention is currently focused: novel materials, characterisation techniques, and device stability. With progress advancing very rapidly, printed electronics is expected to grow over the next decade into a key technology with an enormous economic and social impact.

  8. Scientia Africana - Vol 13, No 1 (2014)

    African Journals Online (AJOL)

    Analytical modeling of pipeline failure in multiphase flow due to corrosion in Niger ... oxide photovoltaic cell for teaching purpose using locally available materials ... Analysis of filtration properties of locally sourced base oil for the formulation of ...

  9. APPUNTI PASOLINIANI PER UN'ORESTIADE AFRICANA

    African Journals Online (AJOL)

    User

    in versi del 1964, L'uomo di Bandung, in P. P. Pasolini, Bestemmia, a cura di G. Chiarcossi e W. Siti ... aver visitato Bombay, Calcutta e Nuova Delhi, in febbraio i tre amici ..... africani mossi dal vento, nei silenzi sovraumani, nel cieco istinto di.

  10. Hypoglycaemic activity of commelina africana and ageratum

    African Journals Online (AJOL)

    Administrator

    Background: Many plants with antidiabetic properties probably act in part through their content of fibre, vitamins, bioactive or mineral ... in Asia and Africa probably due to the adoption of a Western ... Some of the leaves were air dried, ground to ...

  11. A CHAPTER OF EARLY MEDICAL AFRICANA*

    African Journals Online (AJOL)

    1971-05-08

    May 8, 1971 ... each face 252 Rhynland feet long, constructed of earth,. 20 feet in thickness at the base and tapering to 16 feet at the top, 12 feet high. Round the whole ..... cupping was effected by means of the hollow, cut ends of animal horns and blood letting appears to be done. '""".f\\''',(. Fig. 5. A graphic illustration of ...

  12. Scientia Africana - Vol 14, No 1 (2015)

    African Journals Online (AJOL)

    Synthesis, characterization and antibacterial activity of Fe(II) mixed ligands complex of succinic acid and hexamethylenetetramine · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. J. I. Mbonu, M. Ariemudwigho ...

  13. BIOSORPTION OF LEAD BY AFZELIA AFRICANA

    African Journals Online (AJOL)

    Dr Kalu 2

    2013-08-07

    Aug 7, 2013 ... when low concentrations of these heavy metal ions (in the range of 1- 100 ... heavy metals res- ponsible for causing kidney damage, renal disorder, high .... gradually dissociated and the positively charged cadmium ions will ...

  14. Scientia Africana - Vol 10, No 1 (2011)

    African Journals Online (AJOL)

    Open Access DOWNLOAD FULL TEXT ... Preparation and characterization of activated carbon from water hyacinth ... Gender inequality and diseases in Nigeria: a case study of HIV/AIDS and malaria · EMAIL FULL TEXT EMAIL FULL TEXT

  15. UTILIZATION OF Prosopis africana PULP FOR RABBIT

    African Journals Online (AJOL)

    IBB

    protein and less fat and calories per gram than beef, ... unlimited green vegetables, roots and hay, but the ... representing 1450 kg of meat which is equal to an .... iron, 50g; manganese 50g; zinc, 50g; Iodine, 0.78g; Cobalt 0.25g; Copper 5.0g; ...

  16. Scientia Africana - Vol 11, No 2 (2012)

    African Journals Online (AJOL)

    SQLdefend: An automated detection and prevention technique for sql injection vulnerabilities in web applications · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. E.E. Ogheneovo, P.O. Asagba ...

  17. Scientia Africana - Vol 11, No 1 (2012)

    African Journals Online (AJOL)

    Prognostic diagnosis of pelvic inflammatory disease utilizing logical fuzzy ... Some observations on derivatives of orthogonal polynomials · EMAIL FULL TEXT ... output performance of solar power system · EMAIL FULL TEXT EMAIL FULL TEXT

  18. Scientia Africana - Vol 12, No 2 (2013)

    African Journals Online (AJOL)

    Stabilizing the border steady-state solution of two interacting populations · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. N.M. Nafo, E.N. Ekaka-a. Stability analysis of predator-prey interaction with a crowding effect · EMAIL FULL TEXT EMAIL FULL TEXT · DOWNLOAD FULL ...

  19. Molecular Electronics

    DEFF Research Database (Denmark)

    Jennum, Karsten Stein

    This thesis includes the synthesis and characterisation of organic compounds designed for molecular electronics. The synthesised organic molecules are mainly based on two motifs, the obigo(phenyleneethynylenes) (OPE)s and tetrathiafulvalene (TTF) as shown below. These two scaffolds (OPE and TTF......) are chemically merged together to form cruciform-like structures that are an essential part of the thesis. The cruciform molecules were subjected to molecular conductance measurements to explore their capability towards single-crystal field-effect transistors (Part 1), molecular wires, and single electron......, however, was obtained by a study of a single molecular transistor. The investigated OPE5-TTF compound was captured in a three-terminal experiment, whereby manipulation of the molecule’s electronic spin was possible in different charge states. Thus, we demonstrated how the cruciform molecules could...

  20. Electron tube

    Science.gov (United States)

    Suyama, Motohiro [Hamamatsu, JP; Fukasawa, Atsuhito [Hamamatsu, JP; Arisaka, Katsushi [Los Angeles, CA; Wang, Hanguo [North Hills, CA

    2011-12-20

    An electron tube of the present invention includes: a vacuum vessel including a face plate portion made of synthetic silica and having a surface on which a photoelectric surface is provided, a stem portion arranged facing the photoelectric surface and made of synthetic silica, and a side tube portion having one end connected to the face plate portion and the other end connected to the stem portion and made of synthetic silica; a projection portion arranged in the vacuum vessel, extending from the stem portion toward the photoelectric surface, and made of synthetic silica; and an electron detector arranged on the projection portion, for detecting electrons from the photoelectric surface, and made of silicon.

  1. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  2. Electronic Commerce

    Energy Technology Data Exchange (ETDEWEB)

    Laird, N. [NRG Information Services Inc., Calgary, AB (Canada)

    1995-11-01

    The concept of electronic commerce in the gas industry was discussed. It was defined as the integration of communication technology, advanced information processing capability and business standards, to improve effectiveness of the business process. Examples of electronic data interchange from the automotive, airline, and banking industry were given. The objective of using this technology in the gas industry was described as the provision of one electronic facility to make seamless contractual and operational arrangements for moving natural gas across participating pipelines. The benefit of seamless integration - one readily available standard system used by several companies - was highlighted. A list of value-added services such as the free movement of bulletins, directories, nominations,and other documents was provided.

  3. Electron accelerator

    International Nuclear Information System (INIS)

    Abramyan.

    1981-01-01

    The USSR produces an electron accelerator family of a simple design powered straight from the mains. The specifications are given of accelerators ELITA-400, ELITA-3, ELT-2, TEUS-3 and RIUS-5 with maximum electron energies of 0.3 to 5 MeV, a mean power of 10 to 70 kW operating in both the pulsed and the continuous (TEUS-3) modes. Pulsed accelerators ELITA-400 and ELITA-3 and RIUS-5 in which TESLA resonance transformers are used are characterized by their compact size. (Ha)

  4. Electronic cigarette

    OpenAIRE

    Wang, Tao

    2016-01-01

    As we know E-cigarette is becoming increasingly popular all over the world. It is a new product that the most of smoking people would like to buy and use. However, we are not realizing advantages and disadvantages of e-cigarette clearly. My objective was to research the development of electronic cigarette whether it is under control or a good way of marketing. The thesis has two main parts. They include answers to questions what is electronic cigarette and how to manage the whole industry...

  5. Electronic School.

    Science.gov (United States)

    Executive Educator, 1994

    1994-01-01

    This issue of "The Electronic School" features a special forum on computer networking. Articles specifically focus on network operating systems, cabling requirements, and network architecture. Tom Wall argues that virtual reality is not yet ready for classroom use. B.J. Novitsky profiles two high schools experimenting with CD-ROM…

  6. Electronic Government

    DEFF Research Database (Denmark)

    Wimmer, Maria A.; Traunmüller, Roland; Grönlund, Åke

    This book constitutes the refereed proceedings of the 4th International Conference on Electronic Government, EGOV 2005, held in Copenhagen, Denmark, in August 2005. The 30 revised papers presented were carefully reviewed and selected from numerous submissions, and assess the state-of-the-art in e-government/e-governance...

  7. Electronics department

    International Nuclear Information System (INIS)

    1979-01-01

    This report summarizes the activities in 1978 of some of the groups within the Electronics Department. The work covered includes plant protection and operator studies, reliability techniques, application of nuclear techniques to mineral exploration, applied laser physics, computing and, lastly, research instrumentation. (author)

  8. Power electronics

    Indian Academy of Sciences (India)

    Kishore Chatterjee

    This special issue of Sadhana is a compilation of papers selected from those presented at the 7th National Power. Electronics Conference (NPEC), held at the Indian Institute of Technology, Bombay, on 21–23 December 2015. From among the papers presented in NPEC-2017, selected papers were peer-reviewed for ...

  9. Electron linacs

    Energy Technology Data Exchange (ETDEWEB)

    Loew, G A; Schriber, S O [ed.

    1976-11-01

    A study was made of the present status of the thousand or so electron linacs in the world, and future trends in the field. These machines were classified according to their use: medical, industrial, and nuclear physics. In the medical category, two types of electron linacs are discussed: the conventional ones which are used for x-ray and electron therapy, and those which may in the future be used for negative pion therapy. Industrial machines discussed include linacs for radiographic and other specialized applications. In the nuclear physics category, the status of conventional low- and medium-energy as well as high duty cycle linacs is reviewed. The question of how one might obtain a c-w, 1 GeV, 100..mu..A electron linac is raised, and various options using recirculation and stretchers are examined. In this connection, the status of rf superconductivity is summarized. A review is given of linacs for injectors into synchrotrons and e/sup +-/ storage rings, and recent work done to upgrade the only multi-GeV linac, namely SLAC, is described.

  10. Greening Electronics

    DEFF Research Database (Denmark)

    Pizzol, Massimo; Søes Kokborg, Morten; Thomsen, Marianne

    Based on a literature review with focus on hazardous substances in waste electric and electronic equipment (WEEE) and numbers from a Danish treatment facility a flow analysis for specific substances has been conducted. Further, the accessible knowledge on human and environmental effects due...

  11. Electronic seal

    International Nuclear Information System (INIS)

    Musyck, E.

    1981-01-01

    An electronic seal is presented for a volume such as container for fissile materials. The seal encloses a lock for barring the space as well as a device for the detection and the recording of the intervention of the lock. (AF)

  12. Nuclear electronics

    International Nuclear Information System (INIS)

    Friese, T.

    1981-09-01

    A short survey is given on nuclear radiation detectors and nuclear electronics. It is written for newcomers and those, who are not very familiar with this technique. Some additional information is given on typical failures in nuclear measurement systems. (orig.) [de

  13. Electron linacs

    International Nuclear Information System (INIS)

    Loew, G.A.

    1976-01-01

    To study the present status of the thousand or so electron linacs in the world, and future trends in the field, we have classified these machines according to their use: medical, industrial, and nuclear physics. In the medical category, two types of electron linacs are discussed: the conventional ones which are used for X-ray and electron therapy, and those which may in the future be used for negative pion therapy. The section on industrial machines includes linacs for radiographic and other specialized applications. In the nuclear physics category, the status of conventional low- and medium-energy as well as high duty cycle linacs is reviewed. The question of how one might obtain a C.W., 1 GeV, 100 μA electron linac is raised and various options using recirculation and stretchers are examined. In this connection, the status of RF superconductivity is summarized. Following, there is a review of linacs for injectors into synchrotrons and e +- storage rings. The paper ends with a description of recent work done to upgrade the only multi-GeV linac, namely SLAC. (author)

  14. Electronic Nose and Electronic Tongue

    Science.gov (United States)

    Bhattacharyya, Nabarun; Bandhopadhyay, Rajib

    Human beings have five senses, namely, vision, hearing, touch, smell and taste. The sensors for vision, hearing and touch have been developed for several years. The need for sensors capable of mimicking the senses of smell and taste have been felt only recently in food industry, environmental monitoring and several industrial applications. In the ever-widening horizon of frontier research in the field of electronics and advanced computing, emergence of electronic nose (E-Nose) and electronic tongue (E-Tongue) have been drawing attention of scientists and technologists for more than a decade. By intelligent integration of multitudes of technologies like chemometrics, microelectronics and advanced soft computing, human olfaction has been successfully mimicked by such new techniques called machine olfaction (Pearce et al. 2002). But the very essence of such research and development efforts has centered on development of customized electronic nose and electronic tongue solutions specific to individual applications. In fact, research trends as of date clearly points to the fact that a machine olfaction system as versatile, universal and broadband as human nose and human tongue may not be feasible in the decades to come. But application specific solutions may definitely be demonstrated and commercialized by modulation in sensor design and fine-tuning the soft computing solutions. This chapter deals with theory, developments of E-Nose and E-Tongue technology and their applications. Also a succinct account of future trends of R&D efforts in this field with an objective of establishing co-relation between machine olfaction and human perception has been included.

  15. Electronics Industry

    Science.gov (United States)

    2007-01-01

    countries in developing market nations in Asia (such as Korea, Taiwan, Singapore, Malaysia , China and Vietnam). The competition for the knowledge, economic...Intel, Infineon Technologies, STMicroelectronics, Samsung Electronics, Texas Instruments, AMD Spansion, Philips Semiconductor, Freescale... Samsung ($19.7B), #5 Toshiba ($9.8B), #6 TSMC ($9.7B), #7 Hynix ($8.0B) and #8 Renesas ($7.9B) (McGrath, 2007, p. 3). Samsung , headquartered in

  16. Electronic banking

    OpenAIRE

    Gradišnik, Monika

    2017-01-01

    The development of information and communication technology is one of the most important reasons for the incredibly fast changes in business. Electronic commerce is spreading unstoppably in the operations of companies. The creation of new models, such as online banking, online shopping and the like, has sped up the development of the World Wide Web. Owing to the rapid progress of the World Wide Web and technologies for secure business operations, we can barely imagine life today without e...

  17. Electronic Aggression

    Centers for Disease Control (CDC) Podcasts

    2007-11-20

    Aggression is no longer limited to the school yard. New forms of electronic media, such as blogs, instant messaging, chat rooms, email, text messaging, and the internet are providing new arenas for youth violence to occur.  Created: 11/20/2007 by National Center for Injury Prevention and Control, Division of Violence Prevention.   Date Released: 11/28/2007.

  18. ELECTRON GUN

    Science.gov (United States)

    Christofilos, N.C.; Ehlers, K.W.

    1960-04-01

    A pulsed electron gun capable of delivering pulses at voltages of the order of 1 mv and currents of the order of 100 amperes is described. The principal novelty resides in a transformer construction which is disposed in the same vacuum housing as the electron source and accelerating electrode structure of the gun to supply the accelerating potential thereto. The transformer is provided by a plurality of magnetic cores disposed in circumferentially spaced relation and having a plurality of primary windings each inductively coupled to a different one of the cores, and a helical secondary winding which is disposed coaxially of the cores and passes therethrough in circumferential succession. Additional novelty resides in the disposition of the electron source cathode filament input leads interiorly of the transformer secondary winding which is hollow, as well as in the employment of a half-wave filament supply which is synchronously operated with the transformer supply such that the transformer is pulsed during the zero current portions of the half-wave cycle.

  19. Electronic sputtering

    International Nuclear Information System (INIS)

    Johnson, R.E.

    1989-01-01

    Electronic sputtering covers a range of phenomena from electron and photon stimulated desorption from multilayers to fast heavy ion-induced desorption (sputtering) of biomolecules. In this talk the author attempted. Therefore, to connect the detailed studies of argon ejection from solid argon by MeV ions and keV electrons to the sputtering of low temperatures molecular ices by MeV ions then to biomolecule ejection from organic solids. These are related via changing (dE/dx) e , molecular size, and transport processes occurring in materials. In this regard three distinct regions of (dE/dx) e have been identified. Since the talk this picture has been made explicit using a simple spike model for individual impulsive events in which spike interactions are combined linearly. Since that time also the molecular dynamics programs (at Virginia and Uppsala) have quantified both single atom and dimer processes in solid Ar and the momentum transport in large biomolecule sputtering. 5 refs

  20. Detectors - Electronics

    International Nuclear Information System (INIS)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J.

    1998-01-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X → e - converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the 3 He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  1. Electronic materials

    CERN Document Server

    Kwok, H L

    2010-01-01

    The electronic properties of solids have become of increasing importance in the age of information technology. The study of solids and materials, while having originated from the disciplines of physics and chemistry, has evolved independently over the past few decades. The classical treatment of solid-state physics, which emphasized classifications, theories and fundamental physical principles, is no longer able to bridge the gap between materials advances and applications. In particular, the more recent developments in device physics and technology have not necessarily been driven by new conc

  2. Electronic wastes

    Science.gov (United States)

    Regel-Rosocka, Magdalena

    2018-03-01

    E-waste amount is growing at about 4% annually, and has become the fastest growing waste stream in the industrialized world. Over 50 million tons of e-waste are produced globally each year, and some of them end up in landfills causing danger of toxic chemicals leakage over time. E-waste is also sent to developing countries where informal processing of waste electrical and electronic equipment (WEEE) causes serious health and pollution problems. A huge interest in recovery of valuable metals from WEEE is clearly visible in a great number of scientific, popular scientific publications or government and industrial reports.

  3. Electron gun

    International Nuclear Information System (INIS)

    Chen, H.-Y.; Hughes, R.H.

    1979-01-01

    The invention described relates to cathode ray tubes, and particularly to color picture tubes of the type useful in home television receivers and therefore to electron guns. The invention is especially applicable to self-converging tube-yoke combinations with shadow mask tubes of the type having plural-beam in-line guns disposed in a horizontal plane, an apertured mask with vertically oriented slit-shaped apertures, and a screen with vertically oriented phosphor stripes. The invention is not, however, limited to use in such tubes and may in fact be used, e.g., in dot-type shadow mask tubes and index-type tubes. (Auth.)

  4. Bolometer electronics

    International Nuclear Information System (INIS)

    Groenig, D.E.

    1981-01-01

    High quality is required to the electronic which works with bolometer made of metal for measuring the radiation power in plasmaphysical experiments. If the bandwidth is to be 1 kHz, and the time constant of the bolometer is about 160 ms by high overall gain the critical parameters are the noise of the amplifier, pick up to the system, stability and decoupling of common mode signals. The high overall gain is necessary to be able to measure lowest radiation power. The design made is a good approach to the desired property. (orig.) [de

  5. Basic electronics

    CERN Document Server

    Tayal, DC

    2010-01-01

    The second edition of this book incorporates the comments and suggestions of my friends and students who have critically studied the first edition. In this edition the changes and additions have been made and subject matter has been rearranged at some places. The purpose of this text is to provide a comprehensive and up-to-date study of the principles of operation of solid state devices, their basic circuits and application of these circuits to various electronic systems, so that it can serve as a standard text not only for universities and colleges but also for technical institutes. This book

  6. Nuclear electronics

    International Nuclear Information System (INIS)

    Lucero B, E.

    1989-01-01

    The rapid technical development of Colombia over the past years, resulted among others, a considerable increase in the number of measuring instrumentation and testing laboratories, scientific research and metrology centers, in industry, agriculture, public health, education on the nuclear field, etc. IAN is a well organized institution with qualified management, trained staff and reasonably equipped laboratories to carry out tasks as: Metrology, standardization, quality control and maintenance and repair of nuclear instruments. The government of Colombia has adopted a policy to establish and operate through the country maintenance and repair facilities for nuclear instrumentation. This policy is reflected in the organization of electronic laboratories in Bogota-IAN

  7. Adaptación de la metodología de cálculo de huella ecológica para los cultivos de palma africana usando sistemas de información geográfica: estudio de caso Puerto Wilches Santande

    Directory of Open Access Journals (Sweden)

    Claudia Ramírez Cano

    2014-06-01

    Full Text Available En el municipio de Puerto Wilches el monocultivo de palma africana actualmente es un eje trasversal de la economía, modificando la diversidad de los ecosistemas y cultivos tradicionales de la zona. Por lo cual, el objetivo de esta investigación es medir y evaluar los impactos de los cultivos de palma africana en el lapso de 1987 a 2010 adaptando la metodología desarrollada por Mathis Wackernagel y William Rees y algunos aportes de los desarrollos realizados por Juan Luis Doménech, aunando a estos tecnología satelital e indicadores de biocapacidad y déficit ecológico para conocer los requerimientos de espacios y recursos naturales necesarios para la producción de los derivados de la palma. El análisis de la época arrojó para el año 1987 un indicador de huella ecológica con un valor de 1.255 ha/pc, biocapacidad del cultivo 0.470 ha/pc, déficit ecológico correspondiente a -0.785 ha/pc; se estima un valor del 16 % en cuanto a la producción y uso de recursos. Con relación a los indicadores de sostenibilidad, en 2010 se obtuvieron valores de huella ecológica de 5.492 ha/pc, biocapacidad 1.454 ha/pc y déficit ecológico de -4.038 ha/pc, cifras que evidencian los efectos originados por la implementación del monocultivo en la zona, que para la fecha aumento en un 63 % la producción y uso de recursos naturales. Por lo anterior, es necesario y urgente elaborar e implementar políticas de planificación territorial así como alternativas de producción económica para mejorar la calidad ambiental y social del municipio, deteniendo la acelerada antropización de la región.

  8. Practical electronics handbook

    CERN Document Server

    Sinclair, Ian R

    2013-01-01

    Practical Electronics Handbook, Third Edition provides the frequently used and highly applicable principles of electronics and electronic circuits.The book contains relevant information in electronics. The topics discussed in the text include passive and active discrete components; linear and digital I.C.s; microprocessors and microprocessor systems; digital-analogue conversions; computer aids in electronics design; and electronic hardware components.Electronic circuit constructors, service engineers, electronic design engineers, and anyone with an interest in electronics will find the book ve

  9. Electron foreshock

    International Nuclear Information System (INIS)

    Klimas, A.J.

    1985-01-01

    ISEE particle and wave data are noted to furnish substantial support for the basic features of the velocity dispersed model at the foreshock boundary that was proposed by Filbert and Kellogg (1979). Among many remaining discrepancies between this model and observation, it is noted that unstable reduced velocity distributions have been discovered behind the thin boundary proposed by the model, and that these are at suprathermal energies lying far below those explainable in terms of an oscillating, two-stream instability. Although the long-theorized unstable beam of electrons has been found in the foreshock, there is still no ready explanation of the means by which it could have gotten there. 16 references

  10. Sustainable Management of Electronics

    Science.gov (United States)

    To provide information on EPAs strategy for electronics stewardship, certified electronics recyclers and the Challenge; as well as where to donate unwanted electronics, how to calculate benefits, and what's going on with electronics mgmt in their states.

  11. Advanced electron beam techniques

    International Nuclear Information System (INIS)

    Hirotsu, Yoshihiko; Yoshida, Yoichi

    2007-01-01

    After 100 years from the time of discovery of electron, we now have many applications of electron beam in science and technology. In this report, we review two important applications of electron beam: electron microscopy and pulsed-electron beam. Advanced electron microscopy techniques to investigate atomic and electronic structures, and pulsed-electron beam for investigating time-resolved structural change are described. (author)

  12. EDITORIAL: Synaptic electronics Synaptic electronics

    Science.gov (United States)

    Demming, Anna; Gimzewski, James K.; Vuillaume, Dominique

    2013-09-01

    Conventional computers excel in logic and accurate scientific calculations but make hard work of open ended problems that human brains handle easily. Even von Neumann—the mathematician and polymath who first developed the programming architecture that forms the basis of today's computers—was already looking to the brain for future developments before his death in 1957 [1]. Neuromorphic computing uses approaches that better mimic the working of the human brain. Recent developments in nanotechnology are now providing structures with very accommodating properties for neuromorphic approaches. This special issue, with guest editors James K Gimzewski and Dominique Vuillaume, is devoted to research at the serendipitous interface between the two disciplines. 'Synaptic electronics', looks at artificial devices with connections that demonstrate behaviour similar to synapses in the nervous system allowing a new and more powerful approach to computing. Synapses and connecting neurons respond differently to incident signals depending on the history of signals previously experienced, ultimately leading to short term and long term memory behaviour. The basic characteristics of a synapse can be replicated with around ten simple transistors. However with the human brain having around 1011 neurons and 1015 synapses, artificial neurons and synapses from basic transistors are unlikely to accommodate the scalability required. The discovery of nanoscale elements that function as 'memristors' has provided a key tool for the implementation of synaptic connections [2]. Leon Chua first developed the concept of the 'The memristor—the missing circuit element' in 1971 [3]. In this special issue he presents a tutorial describing how memristor research has fed into our understanding of synaptic behaviour and how they can be applied in information processing [4]. He also describes, 'The new principle of local activity, which uncovers a minuscule life-enabling "Goldilocks zone", dubbed the

  13. Age profiles in elephant and mammoth bone assemblages

    Science.gov (United States)

    Haynes, Gary

    1985-11-01

    Age profiles of modern African elephant ( Loxodonta africana) populations are significantly affected by drought conditions that cause local die-offs. Subadult animals die in proportions that may be nearly twice what is recorded in live populations. Such biasing of death sample age profiles might also have occurred during late Pleistocene die-offs of Mammuthus. This comparative study of modern and fossil proboscidean age structures supports a tentative interpretation that late Pleistocene extinction of Mammuthus (at least in the southwestern United States) resulted from severe drought conditions, at which Clovis hunters were witnesses, but not necessarily frequent participants.

  14. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  15. Electron-electron Bremsstrahlung for bound target electrons

    International Nuclear Information System (INIS)

    Haug, E.

    2008-01-01

    For the process of electron-electron (e-e) Bremsstrahlung the momentum and energy distributions of the recoiling electrons are calculated in the laboratory frame. In order to get the differential cross section and the photon spectrum for target electrons which are bound to an atom, these formulae are multiplied by the incoherent scattering function and numerically integrated over the recoil energy. The effect of atomic binding is most pronounced at low energies of the incident electrons and for target atoms of high atomic numbers. The results are compared to those of previous calculations. (authors)

  16. Electron Beam Generation in Tevatron Electron Lenses

    International Nuclear Information System (INIS)

    Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

    2006-01-01

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  17. Electron beam generation in Tevatron electron lenses

    International Nuclear Information System (INIS)

    Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

    2006-01-01

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  18. Complete mitochondrial genome and phylogeny of Pleistocene mammoth Mammuthus primigenius.

    Directory of Open Access Journals (Sweden)

    Evgeny I Rogaev

    2006-03-01

    Full Text Available Phylogenetic relationships between the extinct woolly mammoth (Mammuthus primigenius, and the Asian (Elephas maximus and African savanna (Loxodonta africana elephants remain unresolved. Here, we report the sequence of the complete mitochondrial genome (16,842 base pairs of a woolly mammoth extracted from permafrost-preserved remains from the Pleistocene epoch--the oldest mitochondrial genome sequence determined to date. We demonstrate that well-preserved mitochondrial genome fragments, as long as approximately 1,600-1700 base pairs, can be retrieved from pre-Holocene remains of an extinct species. Phylogenetic reconstruction of the Elephantinae clade suggests that M. primigenius and E. maximus are sister species that diverged soon after their common ancestor split from the L. africana lineage. Low nucleotide diversity found between independently determined mitochondrial genomic sequences of woolly mammoths separated geographically and in time suggests that north-eastern Siberia was occupied by a relatively homogeneous population of M. primigenius throughout the late Pleistocene.

  19. Determinants of elephant distribution at Nazinga Game Ranch, Burkina Faso

    Science.gov (United States)

    Jenks, Jonathan A.; Klaver, Robert W.; Wicks, Zeno W.

    2007-01-01

    We used seasonal ground total counts and remote sensing and GIS technology to relate elephant (Loxodonta africana africana) distribution at Nazinga Game Ranch to environmental and anthropogenic factors. Variables used in analyses were normalized difference vegetation index, elevation, stream density, density of poaching and human illegal activities, distance to dams, distance to rivers, distance to roads, and distance to poaching risk. Contrary to our expectation, road traffic did not disturb elephants. Strong negative relationships were documented between elephant abundance and stream density, distance to dams, and poaching density. Density of poaching and other human illegal activities explained 81%, vegetation greenness 6%, and stream density 3% of the variation in elephant density. Elephant distribution represented a survival strategy affected by poaching, food quality and abundance, and water availability. 

  20. Interplay between electron-phonon and electron-electron interactions

    International Nuclear Information System (INIS)

    Roesch, O.; Gunnarsson, O.; Han, J.E.; Crespi, V.H.

    2005-01-01

    We discuss the interplay between electron-electron and electron-phonon interactions for alkali-doped fullerides and high temperature superconductors. Due to the similarity of the electron and phonon energy scales, retardation effects are small for fullerides. This raises questions about the origin of superconductivity, since retardation effects are believed to be crucial for reducing effects of the Coulomb repulsion in conventional superconductors. We demonstrate that by treating the electron-electron and electron-phonon interactions on an equal footing, superconductivity can be understood in terms of a local pairing. The Jahn-Teller character of the important phonons in fullerides plays a crucial role for this result. To describe effects of phonons in cuprates, we derive a t-J model with phonons from the three-band model. Using exact diagonalization for small clusters, we find that the anomalous softening of the half-breathing phonon as well as its doping dependence can be explained. By comparing the solution of the t-J model with the Hartree-Fock approximation for the three-band model, we address results obtained in the local-density approximation for cuprates. We find that genuine many-body results, due to the interplay between the electron-electron and electron-phonon interactions, play an important role for the the results in the t-J model. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Electronics for LHC Experiments

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This document gathers the abstracts of most presentations made at this workshop on electronics for the large hadron collider (LHC) experiments. The presentations were arranged into 6 sessions: 1) electronics for tracker, 2) trigger electronics, 3) detector control systems, 4) data acquisition, 5) electronics for calorimeters and electronics for muons, and 6) links, power systems, grounding and shielding, testing and quality assurance.

  2. Electronics for LHC Experiments

    International Nuclear Information System (INIS)

    2004-01-01

    This document gathers the abstracts of most presentations made at this workshop on electronics for the large hadron collider (LHC) experiments. The presentations were arranged into 6 sessions: 1) electronics for tracker, 2) trigger electronics, 3) detector control systems, 4) data acquisition, 5) electronics for calorimeters and electronics for muons, and 6) links, power systems, grounding and shielding, testing and quality assurance

  3. Electronics and Information

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Previously founded as CCPITMachinery and Electronics Sub-council and CCOIC Machinery and Electronics Chamber of Corn-merce in June, 1988, CCPIT Electronics Sub-Council and CCOIC Electronics Chamber of Commerce were established in May, 1993, and then renamed as CCPIT Electronics and Information Industry Sub-council and CCOIC Electronics and Infor-mation Industry Chamber of Commerce (CCPITECC) in September 1999.

  4. Electron-electron coincidence spectroscopies at surfaces

    International Nuclear Information System (INIS)

    Stefani, G.; Iacobucci, S.; Ruocco, A.; Gotter, R.

    2002-01-01

    In the past 20 years, a steadily increasing number of electron-electron coincidence experiments on atoms and molecules have contributed to a deeper understanding of electron-electron correlation effects. In more recent years this technique has been extended to the study of solid surfaces. This class of one photon IN two electrons OUT experiments will be discussed with an emphasis on grazing incidence geometry, that is expected to be particularly suited for studying surfaces. The crucial question of which is the dominant mechanism that leads to ejection of pairs of electron from the surface will be addressed. It will be shown that, depending on the kinematics chosen, the correlated behaviour of the pairs of electrons detected might be singled out from independent particle one

  5. Electron Microscopy Center (EMC)

    Data.gov (United States)

    Federal Laboratory Consortium — The Electron Microscopy Center (EMC) at Argonne National Laboratory develops and maintains unique capabilities for electron beam characterization and applies those...

  6. Reflexión sobre la dimensión espectatorial de las películas africanas: o cómo los cines africanos piensan de otra manera en sus públicos / Reflection On the Spectatorial Dimension of African Films: Or How African Cinemas Think About Their Public Different

    Directory of Open Access Journals (Sweden)

    Mahomed Bamba

    2016-03-01

    Full Text Available Este artículo investiga la construcción textual del espectador en varias películas africanas. Un espectador que aparece inscrito «en filigrana» a través de los ges-tos enunciativos y estrategias paratextuales de cineastas que siguen la lógica poética del cine de autor. Es a través del análisis de estas estrategias estilísticas y narrativas, de los recursos simbólicos utilizados, de las huellas metadiscursivas presentes en los textos, como se puede averiguar, más allá de las intenciones expresadas por los propios cineastas, o de los resultados en taquilla, en qué medida los autores han pensado o no en los públicos africanos, y si se dirigen exclusivamente a ellos.Palabras clave: relato, sistema textual, paratexto, espectador implícito, semiopragmática, griot, cine de autor.AbstractThis article explores the textual construction of the spectator in various African films. A spectator that seems to be registered as a ‘watermark’ through the expository gestures and paratextual strategies of filmmakers that follow the poetic logic of auteur cinema. It is through the analysis of these stylistic and narrative strategies, of the symbolic resources used, and of the metadiscursive traces present in the texts, that the extent to which the authors have taken into consideration the African audience, and whether or not they are aiming exclusively at them, can be explored - even in terms beyond those directly expressed by the filmmakers themselves.Keywords: story, textual system, paratext, implicit spectator, semio-pragmatics, griot, auteur cinema

  7. Plasmaspheric electron content

    International Nuclear Information System (INIS)

    Hartmann, G.K.

    1978-01-01

    Measurements of the plasmaspheric electron content are reviewed with particular reference to the ATS-6 radio beacon experiment. From the review, it appears likely that measurement of the plasmaspheric electron content is the only one capable of monitoring electron fluxes continuously between L 1 and L 2. Some recent important results deduced from plasmaspheric electron content measurements are discussed

  8. Introduction to electronics

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    Electronics in HEP experiments: specificities and evolution The Art of Electronics: is there something beyond Ohm's law? Basic building blocks of Analog electronics: quickly understanding a schematic Charge preamps, current preamps and future preamps, shaping and the rest Electronics noise: fundamental and practical Evolution of technology: ASICs, FPGAs...

  9. Introduction to Electronics course

    CERN Multimedia

    CERN. Geneva HR-RFA

    2006-01-01

    Electronics in HEP experiments: specificities and evolution The Art of Electronics: is there something beyond Ohm's law? Basic building blocks of Analog electronics: quickly understanding a schematic Charge preamps, current preamps and future preamps, shaping and the rest Electronics noise: fundamental and practical Evolution of technology: ASICs, FPGAs...

  10. Electronics engineer's reference book

    CERN Document Server

    Mazda, F F

    1989-01-01

    Electronics Engineer's Reference Book, Sixth Edition is a five-part book that begins with a synopsis of mathematical and electrical techniques used in the analysis of electronic systems. Part II covers physical phenomena, such as electricity, light, and radiation, often met with in electronic systems. Part III contains chapters on basic electronic components and materials, the building blocks of any electronic design. Part IV highlights electronic circuit design and instrumentation. The last part shows the application areas of electronics such as radar and computers.

  11. Electron transfer reactions

    CERN Document Server

    Cannon, R D

    2013-01-01

    Electron Transfer Reactions deals with the mechanisms of electron transfer reactions between metal ions in solution, as well as the electron exchange between atoms or molecules in either the gaseous or solid state. The book is divided into three parts. Part 1 covers the electron transfer between atoms and molecules in the gas state. Part 2 tackles the reaction paths of oxidation states and binuclear intermediates, as well as the mechanisms of electron transfer. Part 3 discusses the theories and models of the electron transfer process; theories and experiments involving bridged electron transfe

  12. Electron-electron interactions in artificial graphene

    Science.gov (United States)

    Rasanen, Esa

    2013-03-01

    Recent advances in the creation and modulation of graphenelike systems are introducing a science of ``designer Dirac materials.'' In its original definition, artificial graphene is a man-made nanostructure that consists of identical potential wells (quantum dots) arranged in an adjustable honeycomb lattice in the two-dimensional electron gas. As our ability to control the quality of artificial graphene samples improves, so grows the need for an accurate theory of its electronic properties, including the effects of electron-electron interactions. Here we determine those effects on the band structure and on the emergence of Dirac points, and discuss future investigations and challenges in this field.

  13. Electronic payment systems

    OpenAIRE

    Mláka, Michal

    2010-01-01

    This bachelor thesis analysis issue of electronic payment systems. It discusses their use for payments on the internet and sending funds via e-mail. The first part is devoted to the theoretical definition and legislation of the issuance of electronic money and activities of electronic money institutions. The main part of the work clearly focuses on the use of e-wallets, which is an integral part of electronic payment systems. E-wallet of electronic payment system Moneybookers is considered as...

  14. Electronics engineer's reference book

    CERN Document Server

    Turner, L W

    1976-01-01

    Electronics Engineer's Reference Book, 4th Edition is a reference book for electronic engineers that reviews the knowledge and techniques in electronics engineering and covers topics ranging from basics to materials and components, devices, circuits, measurements, and applications. This edition is comprised of 27 chapters; the first of which presents general information on electronics engineering, including terminology, mathematical equations, mathematical signs and symbols, and Greek alphabet and symbols. Attention then turns to the history of electronics; electromagnetic and nuclear radiatio

  15. Practical microwave electron devices

    CERN Document Server

    Meurant, Gerard

    2013-01-01

    Practical Microwave Electron Devices provides an understanding of microwave electron devices and their applications. All areas of microwave electron devices are covered. These include microwave solid-state devices, including popular microwave transistors and both passive and active diodes; quantum electron devices; thermionic devices (including relativistic thermionic devices); and ferrimagnetic electron devices. The design of each of these devices is discussed as well as their applications, including oscillation, amplification, switching, modulation, demodulation, and parametric interactions.

  16. Neutrinos in the Electron

    International Nuclear Information System (INIS)

    Koschmieder, E. L.

    2007-01-01

    I will show that one half of the rest mass of the electron consists of electron neutrinos and that the other half of the rest mass of the electron consists of the mass in the energy of electric oscillations. With this composition we can explain the rest mass of the electron, its charge, its spin and its magnetic moment We have also determined the rest masses of the muon neutrino and the electron neutrino

  17. Electron-electron interactions in disordered systems

    CERN Document Server

    Efros, AL

    1985-01-01

    ``Electron-Electron Interactions in Disordered Systems'' deals with the interplay of disorder and the Coulomb interaction. Prominent experts give state-of-the-art reviews of the theoretical and experimental work in this field and make it clear that the interplay of the two effects is essential, especially in low-dimensional systems.

  18. VIRTUAL ELECTRONIC COMPONENTS OF THE ELECTRONIC EQUIPMENT

    Directory of Open Access Journals (Sweden)

    E. Lazarevich

    2013-01-01

    Full Text Available The article is present new idea of the creation, developments and improvements of the electronic equipment of complex systems by means of the virtual electronic components. The idea of the virtual electronic components is a presentation and perception of the creation and developments of the equipment on two forming: real – in the manner of standard marketed block of the intellectual property and image – in the manner of virtual component. The real component in most cases slows the development of the electronic equipment. The imaginary component is the «locomotive» of development of the electronic equipment. The Imaginary component contains the scientific has brushed against developer. The scientific has brushed against developer reveals of itself in the manner of virtual component on the modern level of the design rates of microelectronics.

  19. Practical XHV electron gun

    International Nuclear Information System (INIS)

    Urata, Tomohiro; Ishikawa, Tsuyoshi; Cho, Boklae; Oshima, Chuhei

    2008-01-01

    We have developed practical XHV chambers of a electron gun, of which the operating pressures are 1x10 -9 Pa in a stainless-steel one and 4x10 -9 Pa in a permalloy one. By mounting a noble single-atom electron source with high brightness and high spatial coherence on the electron gun including electron optics, we demonstrated highly collimated electron-beam emission: ∼80% of the total emission current entered the electron optics. This ratio was two or three orders of magnitude higher than those of the conventional electron sources. In XHV, in addition, we confirmed stable electron emission up to 20 nA, which results in the specimen current high enough for scanning electron microscopes. (author)

  20. A superconducting electron spectrometer

    International Nuclear Information System (INIS)

    Guttormsen, M.; Huebel, H.; Grumbkow, A. von

    1983-03-01

    The set-up and tests of an electron spectrometer for in-beam conversion electron measurements are described. A superconducting solenoid is used to transport the electrons from the target to cooled Si(Li) detectors. The solenoid is designed to produce either a homogeneous axially symmetric field of up to 2 Tesla or a variety of field profiles by powering the inner and outer set of coils of the solenoid separately. The electron trajectories resulting for various field profiles are discussed. In-beam electron spectra taken in coincidence with electrons, gammas and alpha-particles are shown. (Auth.)

  1. Electronics for dummies

    CERN Document Server

    Shamieh

    2015-01-01

    Explore the basic concepts of electronics, build your electronics workbench, and begin creating fun electronics projects right away! Electronics For Dummies, 3rd Edition is your guide to the world of electronics. Spanning circuitry, wiring, robotics, transmitters, amplifiers, and more, this book demystifies electricity basics and beyond. The third edition offers new content revised to reflect the latest advancements in the electronics field, and it offers full color project examples to spark your creativity and inspire you to put your new skills to use! Packed with projects that can be comple

  2. RHIC electron lenses upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Altinbas, Z. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Binello, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Costanzo, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Drees, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Harvey, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mi, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Michnoff, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Pikin, A. I. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Samms, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Shrey, T. C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Schoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tan, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015, two electron lenses were used to partially compensate for the head-on beam-beam effect for the first time. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.

  3. Electron emitting filaments for electron discharge devices

    International Nuclear Information System (INIS)

    Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

    1988-01-01

    This patent describes an electron emitting device for use in an electron discharge system. It comprises: a filament having a pair of terminal ends, electrical supply means for supplying electrical power to the terminal ends of the filament for directly heating the filament by the passage of an electrical current along the filament between the terminal ends, the filament being substantially tapered in cross section continuously in one direction from one of its pair of terminal ends to another of its pair of terminal ends to achieve uniform heating of the filament along the length thereof by compensating for the nonuniform current along the filament due to the emission of electrons therefrom

  4. Narrow electron injector for ballistic electron spectroscopy

    International Nuclear Information System (INIS)

    Kast, M.; Pacher, C.; Strasser, G.; Gornik, E.

    2001-01-01

    A three-terminal hot electron transistor is used to measure the normal energy distribution of ballistic electrons generated by an electron injector utilizing an improved injector design. A triple barrier resonant tunneling diode with a rectangular transmission function acts as a narrow (1 meV) energy filter. An asymmetric energy distribution with its maximum on the high-energy side with a full width at half maximum of ΔE inj =10 meV is derived. [copyright] 2001 American Institute of Physics

  5. Electronic Submission of Labels

    Science.gov (United States)

    Pesticide registrants can provide draft and final labels to EPA electronically for our review as part of the pesticide registration process. The electronic submission of labels by registrants is voluntary but strongly encouraged.

  6. Electron scattering from pyrimidine

    International Nuclear Information System (INIS)

    Colmenares, Rafael; Fuss, Martina C; García, Gustavo; Oller, Juan C; Muñoz, Antonio; Blanco, Francisco; Almeida, Diogo; Limão-Vieira, Paulo

    2014-01-01

    Electron scattering from pyrimidine (C 4 H 4 N 2 ) was investigated over a wide range of energies. Following different experimental and theoretical approaches, total, elastic and ionization cross sections as well as electron energy loss distributions were obtained.

  7. THE ELECTRONIC SIGNATURE

    Directory of Open Access Journals (Sweden)

    Voiculescu Madalina Irena

    2009-05-01

    Full Text Available Article refers to significance and the digital signature in electronic commerce. Internet and electronic commerce open up many new opportunities for the consumer, yet, the security (or perceived lack of security of exchanging personal and financial data

  8. Laboratory Handbook Electronics

    CERN Multimedia

    1966-01-01

    Laboratory manual 1966 format A3 with the list of equipment cables, electronic tubes, chassis, diodes transistors etc. One of CERN's first material catalogue for construction components for mechanical and electronic chassis.

  9. Presidential Electronic Records Library

    Data.gov (United States)

    National Archives and Records Administration — PERL (Presidential Electronic Records Library) used to ingest and provide internal access to the Presidential electronic Records of the Reagan, Bush, and Clinton...

  10. Chapter 9: Electronics

    International Nuclear Information System (INIS)

    Grupen, Claus; Shwartz, Boris A.

    2006-01-01

    Sophisticated front-end electronics are a key part of practically all modern radiation detector systems. This chapter introduces the basic principles and their implementation. Topics include signal acquisition, electronic noise, pulse shaping (analog and digital), and data readout techniques

  11. Certified Electronics Recyclers

    Science.gov (United States)

    Learn how EPA encourages all electronics recyclers become certified by demonstrating to an accredited, independent third-party auditor and that they meet specific standards to safely recycle and manage electronics.

  12. Reversibly Bistable Flexible Electronics

    KAUST Repository

    Alfaraj, Nasir

    2015-01-01

    Introducing the notion of transformational silicon electronics has paved the way for integrating various applications with silicon-based, modern, high-performance electronic circuits that are mechanically flexible and optically semitransparent

  13. Electronic Signature Policy

    Science.gov (United States)

    Establishes the United States Environmental Protection Agency's approach to adopting electronic signature technology and best practices to ensure electronic signatures applied to official Agency documents are legally valid and enforceable

  14. Electronics Industry Study Report

    National Research Council Canada - National Science Library

    Belt, David; Fellows, John R; Kameru, Philip; Nazaroff, Boris-Frank A; Pauroso, Anthony; Schulz, Frederick; Ballew, Bob; Bond, Thomas; Demers, Stephy; Kirkpatrick, Steve

    2005-01-01

    This paper provides a national strategy for the US electronics industry. Electronics is one of the largest industries in the US and plays a critical role in almost every aspect of national security...

  15. Electron microscopy for Engineers

    International Nuclear Information System (INIS)

    Jones, I P

    2009-01-01

    This paper reviews the application of (mainly) Transmission Electron Microscopy (TEM) in an engineering context. The first two sections are TEM and chemical in nature; the final three sections are more general and include aspects of Scanning Electron Microscopy (SEM).

  16. ELSA electron stretcher devices

    International Nuclear Information System (INIS)

    1979-10-01

    The use of an electron stretcher ring at the Bonn electron synchrotron is discussed. The construction of the proposed ring is described, and the costs are estimated. Possible experiments using this ring are discussed. (HSI)

  17. Electron shuttles in biotechnology.

    Science.gov (United States)

    Watanabe, Kazuya; Manefield, Mike; Lee, Matthew; Kouzuma, Atsushi

    2009-12-01

    Electron-shuttling compounds (electron shuttles [ESs], or redox mediators) are essential components in intracellular electron transfer, while microbes also utilize self-produced and naturally present ESs for extracellular electron transfer. These compounds assist in microbial energy metabolism by facilitating electron transfer between microbes, from electron-donating substances to microbes, and/or from microbes to electron-accepting substances. Artificially supplemented ESs can create new routes of electron flow in the microbial energy metabolism, thereby opening up new possibilities for the application of microbes to biotechnology processes. Typical examples of such processes include halogenated-organics bioremediation, azo-dye decolorization, and microbial fuel cells. Herein we suggest that ESs can be applied widely to create new microbial biotechnology processes.

  18. Electronic Science Seminar

    Directory of Open Access Journals (Sweden)

    Geidarov P.Sh.

    2015-09-01

    Full Text Available The structure of electronic scientific seminar, which provides a high level of quality of the objectivity in the evaluation of scientific papers, including dissertations, is described. Conditions for the implementation of electronic scientific seminar are also considered.

  19. Copyright of Electronic Publishing.

    Science.gov (United States)

    Dong, Elaine; Wang, Bob

    2002-01-01

    Analyzes the importance of copyright, considers the main causes of copyright infringement in electronic publishing, discusses fair use of a copyrighted work, and suggests methods to safeguard copyrighted electronic publishing, including legislation, contracts, and technology. (Author/LRW)

  20. Paleoclassical electron heat transport

    International Nuclear Information System (INIS)

    Callen, J.D.

    2005-01-01

    Radial electron heat transport in low collisionality, magnetically-confined toroidal plasmas is shown to result from paleoclassical Coulomb collision processes (parallel electron heat conduction and magnetic field diffusion). In such plasmas the electron temperature equilibrates along magnetic field lines a long length L, which is the minimum of the electron collision length and a maximum effective half length of helical field lines. Thus, the diffusing field lines induce a radial electron heat diffusivity M ≅ L/(πR 0q ) ∼ 10 >> 1 times the magnetic field diffusivity η/μ 0 ≅ ν e (c/ω p ) 2 . The paleoclassical electron heat flux model provides interpretations for many features of 'anomalous' electron heat transport: magnitude and radial profile of electron heat diffusivity (in tokamaks, STs, and RFPs), Alcator scaling in high density plasmas, transport barriers around low order rational surfaces and near a separatrix, and a natural heat pinch (or minimum temperature gradient) heat flux form. (author)

  1. Extreme environment electronics

    CERN Document Server

    Cressler, John D

    2012-01-01

    Unfriendly to conventional electronic devices, circuits, and systems, extreme environments represent a serious challenge to designers and mission architects. The first truly comprehensive guide to this specialized field, Extreme Environment Electronics explains the essential aspects of designing and using devices, circuits, and electronic systems intended to operate in extreme environments, including across wide temperature ranges and in radiation-intense scenarios such as space. The Definitive Guide to Extreme Environment Electronics Featuring contributions by some of the world's foremost exp

  2. Electronic theodolite intersection systems

    OpenAIRE

    Bingley, R. M.

    1990-01-01

    The development of electronic surveying instruments, such as electronic theodolites, and concurrent advances in computer technology, has revolutionised engineering surveying; one of the more recent examples being the introduction of Electronic Theodolite Intersection Systems (ETISs). An ETIS consists of two or more electronic theodolites and a computer, with peripheral hardware and suitable software. The theoretical principles on which they are based have been known for a long time, but ...

  3. Electron-attachment processes

    International Nuclear Information System (INIS)

    Christophorou, L.G.; McCorkle, D.L.; Christodoulides, A.A.

    1982-01-01

    Topics covered include: (1) modes of production of negative ions, (2) techniques for the study of electron attachment processes, (3) dissociative electron attachment to ground-state molecules, (4) dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), (5) molecular parent negative ions, and (6) negative ions formed by ion-pair processes and by collisions of molecules with ground state and Rydberg atoms

  4. Handbook on electronic commerce

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, M. [Illinois Univ., Urbana, IL (United States). Beckman Inst. for Advanced Science and Technology; Blanning, R. [Vanderbilt Univ., Nashville, TN (United States). Owen Graduate School of Management; Strader, T. [Iowa State Univ., Ames, IA (United States). Management Information Systems; Whinston, A. [eds.] [Texas Univ., Austin, TX (United States). Dept. of Management Science and Information Systems

    2000-07-01

    The world is undergoing a revolution to a digital economy, with pronounced implications for corporate strategy, marketing, operations, information systems, customer services, global supply-chain management, and product distribution. This handbook examines the aspects of electronic commerce, including electronic storefront, on-line business, consumer interface, business-to-business networking, digital payment, legal issues, information product development, and electronic business models. Indispensable for academics, students and professionals who are interested in Electronic Commerce and Internet Business. (orig.)

  5. Educação permanente em saúde e as Diretrizes Curriculares Nacionais para Educação das relações étnico-raciais e para ensino de História e Cultura Afro-Brasileira e Africana

    Directory of Open Access Journals (Sweden)

    Rosana Batista Monteiro

    Full Text Available Resumo Este texto é um ensaio sobre algumas contribuições que o curso de especialização em Saúde da Mulher Negra pode ter produzido para a abordagem dos conteúdos relacionados nas Diretrizes Curriculares Nacionais para a Educação das Relações Étnico-raciais e para o Ensino de História e Cultura Afro-brasileira e Africana, bem como em atenção à Política Nacional de Saúde Integral da População Negra, com destaque para a educação permanente. A partir de breve contextualização sobre o debate no campo das relações raciais e ações afirmativas no Brasil passamos a apresentar a organização e funcionamento do curso, destacando seus objetivos, conteúdos, estratégias. Com foco nos profissionais da saúde, o curso contou com significativa presença de profissionais da educação básica pública, municipal e estadual, das cidades de São Luís e Pinheiro, no Maranhão, implicando a discussão do tema saúde da população negra (especialmente da mulher negra no âmbito da escola. O curso propiciou a elaboração de projetos de pesquisa relacionados diretamente com o atendimento à saúde de mulheres negras e sua relação com processos formativos de profissionais da área da saúde, bem como educação escolar e saúde de mulheres negras. Pode-se concluir, ainda que provisoriamente, que o curso, na perspectiva da educação permanente, resultou em estratégia eficaz para o desenvolvimento de conteúdos relacionados às DCNERER e, especialmente, de viabilização de implementação da Política Nacional de Saúde Integral da População Negra, realizadas ou desencadeadas nos serviços de saúde pelos cursistas.

  6. Electron Cyclotron Resonances in Electron Cloud Dynamics

    International Nuclear Information System (INIS)

    Celata, Christine; Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

    2008-01-01

    We report a previously unknown resonance for electron cloud dynamics. The 2D simulation code 'POSINST' was used to study the electron cloud buildup at different z positions in the International Linear Collider positron damping ring wiggler. An electron equilibrium density enhancement of up to a factor of 3 was found at magnetic field values for which the bunch frequency is an integral multiple of the electron cyclotron frequency. At low magnetic fields the effects of the resonance are prominent, but when B exceeds ∼(2 pi mec/(elb)), with lb = bunch length, effects of the resonance disappear. Thus short bunches and low B fields are required for observing the effect. The reason for the B field dependence, an explanation of the dynamics, and the results of the 2D simulations and of a single-particle tracking code used to elucidate details of the dynamics are discussed

  7. Syringe injectable electronics

    Science.gov (United States)

    Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M.

    2015-01-01

    Seamless and minimally-invasive three-dimensional (3D) interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating syringe injection and subsequent unfolding of submicrometer-thick, centimeter-scale macroporous mesh electronics through needles with a diameter as small as 100 micrometers. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with > 90% device yield. We demonstrate several applications of syringe injectable electronics as a general approach for interpenetrating flexible electronics with 3D structures, including (i) monitoring of internal mechanical strains in polymer cavities, (ii) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (iii) in vivo multiplexed neural recording. Moreover, syringe injection enables delivery of flexible electronics through a rigid shell, delivery of large volume flexible electronics that can fill internal cavities and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics. PMID:26053995

  8. Syringe-injectable electronics.

    Science.gov (United States)

    Liu, Jia; Fu, Tian-Ming; Cheng, Zengguang; Hong, Guosong; Zhou, Tao; Jin, Lihua; Duvvuri, Madhavi; Jiang, Zhe; Kruskal, Peter; Xie, Chong; Suo, Zhigang; Fang, Ying; Lieber, Charles M

    2015-07-01

    Seamless and minimally invasive three-dimensional interpenetration of electronics within artificial or natural structures could allow for continuous monitoring and manipulation of their properties. Flexible electronics provide a means for conforming electronics to non-planar surfaces, yet targeted delivery of flexible electronics to internal regions remains difficult. Here, we overcome this challenge by demonstrating the syringe injection (and subsequent unfolding) of sub-micrometre-thick, centimetre-scale macroporous mesh electronics through needles with a diameter as small as 100 μm. Our results show that electronic components can be injected into man-made and biological cavities, as well as dense gels and tissue, with >90% device yield. We demonstrate several applications of syringe-injectable electronics as a general approach for interpenetrating flexible electronics with three-dimensional structures, including (1) monitoring internal mechanical strains in polymer cavities, (2) tight integration and low chronic immunoreactivity with several distinct regions of the brain, and (3) in vivo multiplexed neural recording. Moreover, syringe injection enables the delivery of flexible electronics through a rigid shell, the delivery of large-volume flexible electronics that can fill internal cavities, and co-injection of electronics with other materials into host structures, opening up unique applications for flexible electronics.

  9. Electrons in Condensed Matter

    Indian Academy of Sciences (India)

    three freely moving electrons. The value at room temperature is 3.1 k B; the electronic specific heat is missing! The next stage in the electronic theory of solids clears up ..... a big dog? We do not know the reasons yet. As it turns out for many fundamentally interesting phenomena, colossal magneto- resistance may also find ...

  10. Arduino electronics blueprints

    CERN Document Server

    Wilcher, Don

    2015-01-01

    This book is intended for those who want to learn about electronics and coding by building amazing devices and gadgets with Arduino. If you are an experienced developer who understands the basics of electronics, then you can quickly learn how to build smart devices using Arduino. The only experience needed is a desire to learn about electronics, circuit breadboarding, and coding.

  11. EFFECTIVE ELECTRONIC TUTORIAL

    Directory of Open Access Journals (Sweden)

    Andrei A. Fedoseev

    2014-01-01

    Full Text Available The article analyzes effective electronic tutorials creation and application based on the theory of pedagogy. Herewith the issues of necessary electronic tutorial functional, ways of the educational process organization with the use of information and communication technologies and the logistics of electronic educational resources are touched upon. 

  12. Embracing Electronic Publishing.

    Science.gov (United States)

    Wills, Gordon

    1996-01-01

    Electronic publishing is the grandest revolution in the capture and dissemination of academic and professional knowledge since Caxton developed the printing press. This article examines electronic publishing, describes different electronic publishing scenarios (authors' cooperative, consolidator/retailer/agent oligopsony, publisher oligopoly), and…

  13. Soldering in electronics assembly

    CERN Document Server

    Judd, Mike

    2013-01-01

    Soldering in Electronics Assembly discusses several concerns in soldering of electronic assemblies. The book is comprised of nine chapters that tackle different areas in electronic assembly soldering. Chapter 1 discusses the soldering process itself, while Chapter 2 covers the electronic assemblies. Chapter 3 talks about solders and Chapter 4 deals with flux. The text also tackles the CS and SC soldering process. The cleaning of soldered assemblies, solder quality, and standards and specifications are also discussed. The book will be of great use to professionals who deal with electronic assem

  14. Quantitative secondary electron detection

    Science.gov (United States)

    Agrawal, Jyoti; Joy, David C.; Nayak, Subuhadarshi

    2018-05-08

    Quantitative Secondary Electron Detection (QSED) using the array of solid state devices (SSD) based electron-counters enable critical dimension metrology measurements in materials such as semiconductors, nanomaterials, and biological samples (FIG. 3). Methods and devices effect a quantitative detection of secondary electrons with the array of solid state detectors comprising a number of solid state detectors. An array senses the number of secondary electrons with a plurality of solid state detectors, counting the number of secondary electrons with a time to digital converter circuit in counter mode.

  15. Electron distribution function in electron-beam-excited plasmas

    International Nuclear Information System (INIS)

    Brau, C.A.

    1976-01-01

    In monatomic plasmas excited by high-intensity relativistic electron beams, the electron secondary distribution function is dominated by elastic electron-electron collisions at low electron energies and by inelastic electron-atom collisions at high electron energies (above the excitation threshold). Under these conditions, the total rate of excitation by inelastic collisions is limited by the rate at which electron-electron collisions relax the distribution function in the neighborhood of the excitation threshold. To describe this effect quantitatively, an approximate analytic solution of the electron Boltzmann equation is obtained, including both electron-electron and inelastic collisions. The result provides a simple formula for the total rate of excitation

  16. Molecular electron affinities

    International Nuclear Information System (INIS)

    Fukuda, E.K.

    1983-01-01

    Molecular electron affinities have historically been difficult quantities to measure accurately. These difficulties arise from differences in structure between the ion and neutral as well as the existence of excited negative ion states. To circumvent these problems, relative electron affinities were determined in this dissertation by studying equilibrium electron transfer reactions using a pulsed ion cyclotron resonance (ICR) spectrometer. Direct measurement of ion and neutral concentrations for reactions of the general type, A - + B = B - + A, allow calculation of the equilibrium constant and, therefore, the free energy change. The free energy difference is related to the difference in electron affinities between A and B. A relative electron affinity scale covering a range of about 45 kcal/mol was constructed with various substituted p-benzoquinones, nitrobenzenes, anhydrides, and benzophenones. To assign absolute electron affinities, various species with accurately known electron affinities are tied to the scale via ion-cyclotron double resonance bracketing techniques. After the relative scale is anchored to these species with well-known electron affinities, the scale is then used as a check on other electron affinity values as well as generating new electron affinity values. Many discrepancies were found between the electron affinities measured using the ICR technique and previous literature determinations

  17. Nonambipolar electron source

    International Nuclear Information System (INIS)

    Longmier, B.; Baalrud, S.; Hershkowitz, N.

    2006-01-01

    A radio frequency (rf) plasma-based electron source that does not rely on electron emission at a cathode surface has been constructed. All of the random electron flux incident on an exit aperture is extracted through an electron sheath resulting in total nonambipolar flow within the device when the ratio of the ion loss area to the electron loss area is approximately equal to the square root of the ratio of the ion mass to the electron mass, and the ion sheath potential drop at the chamber walls is much larger than T e /e. The nonambipolar electron source (NES) has an axisymmetric magnetic field of 100 G at the extraction aperture that results in a uniform plasma potential across the aperture, allowing the extraction of all the incident electron flux without the use of grids. A prototype NES has produced 15 A of continuous electron current, using 15 SCCM (SCCM denotes cubic centimeter per minute at STP) Ar, 1200 W rf power at 13.56 MHz, and 6 times gas utilization. Alternatively 8 A of electron current can be produced, using 3 SCCM Ar at 1200 W rf and 20 times gas utilization. NES could replace hollow cathode electron sources in a wide variety of applications

  18. High brightness electron accelerator

    International Nuclear Information System (INIS)

    Sheffield, R.L.; Carlsten, B.E.; Young, L.M.

    1994-01-01

    A compact high brightness linear accelerator is provided for use, e.g., in a free electron laser. The accelerator has a first plurality of accelerating cavities having end walls with four coupling slots for accelerating electrons to high velocities in the absence of quadrupole fields. A second plurality of cavities receives the high velocity electrons for further acceleration, where each of the second cavities has end walls with two coupling slots for acceleration in the absence of dipole fields. The accelerator also includes a first cavity with an extended length to provide for phase matching the electron beam along the accelerating cavities. A solenoid is provided about the photocathode that emits the electrons, where the solenoid is configured to provide a substantially uniform magnetic field over the photocathode surface to minimize emittance of the electrons as the electrons enter the first cavity. 5 figs

  19. Electronic equipment packaging technology

    CERN Document Server

    Ginsberg, Gerald L

    1992-01-01

    The last twenty years have seen major advances in the electronics industry. Perhaps the most significant aspect of these advances has been the significant role that electronic equipment plays in almost all product markets. Even though electronic equipment is used in a broad base of applications, many future applications have yet to be conceived. This versatility of electron­ ics has been brought about primarily by the significant advances that have been made in integrated circuit technology. The electronic product user is rarely aware of the integrated circuits within the equipment. However, the user is often very aware of the size, weight, mod­ ularity, maintainability, aesthetics, and human interface features of the product. In fact, these are aspects of the products that often are instrumental in deter­ mining its success or failure in the marketplace. Optimizing these and other product features is the primary role of Electronic Equipment Packaging Technology. As the electronics industry continues to pr...

  20. Automotive electronics design fundamentals

    CERN Document Server

    Zaman, Najamuz

    2015-01-01

    This book explains the topology behind automotive electronics architectures and examines how they can be profoundly augmented with embedded controllers. These controllers serve as the core building blocks of today’s vehicle electronics. Rather than simply teaching electrical basics, this unique resource focuses on the fundamental concepts of vehicle electronics architecture, and details the wide variety of Electronic Control Modules (ECMs) that enable the increasingly sophisticated "bells & whistles" of modern designs.  A must-have for automotive design engineers, technicians working in automotive electronics repair centers and students taking automotive electronics courses, this guide bridges the gap between academic instruction and industry practice with clear, concise advice on how to design and optimize automotive electronics with embedded controllers.

  1. Ion plasma electron gun

    International Nuclear Information System (INIS)

    Wakalopulos, G.

    1976-01-01

    In the disclosed electron gun positive ions generated by a hollow cathode plasma discharge in a first chamber are accelerated through control and shield grids into a second chamber containing a high voltage cold cathode. These positive ions bombard a surface of the cathode causing the cathode to emit secondary electrons which form an electron beam having a distribution adjacent to the cathode emissive surface substantially the same as the distribution of the ion beam impinging upon the cathode. After passing through the grids and the plasma discharge chamber, the electron beam exits from the electron gun via a foil window. Control of the generated electron beam is achieved by applying a relatively low control voltage between the control grid and the electron gun housing (which resides at ground potential) to control the density of the positive ions bombarding the cathode

  2. Seeing with electrons

    International Nuclear Information System (INIS)

    Nellist, P.

    2006-01-01

    Commercially available lens correctors are extending the reach of electron microscopes to unprecedented atomic scales, as Peter Nellist describes. The electron microscope was invented in 1933 and is based on the principle that electrons have a wavelength that is inversely proportional to their momentum. There are two basic types: transmission electron microscopes and scanning electron microscopes, plus a hybrid of the two. The lenses in an electron microscope are provided by electromagnetic fields, but they suffer from spherical aberration. The addition of octupole and quadrupole corrector fields has improved the resolution of the electron microscope to better than 0.1 nm in the last decade. The next step is to correct for chromatic aberration, after which the resolution of the microscope will probably be limited by the size of the atom itself. (U.K.)

  3. Engineered phages for electronics.

    Science.gov (United States)

    Cui, Yue

    2016-11-15

    Phages are traditionally widely studied in biology and chemistry. In recent years, engineered phages have attracted significant attentions for functionalization or construction of electronic devices, due to their specific binding, catalytic, nucleating or electronic properties. To apply the engineered phages in electronics, these are a number of interesting questions: how to engineer phages for electronics? How are the engineered phages characterized? How to assemble materials with engineered phages? How are the engineered phages micro or nanopatterned? What are the strategies to construct electronics devices with engineered phages? This review will highlight the early attempts to address these questions and explore the fundamental and practical aspects of engineered phages in electronics, including the approaches for selection or expression of specific peptides on phage coat proteins, characterization of engineered phages in electronics, assembly of electronic materials, patterning of engineered phages, and construction of electronic devices. It provides the methodologies and opens up ex-cit-ing op-por-tu-ni-ties for the development of a variety of new electronic materials and devices based on engineered phages for future applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Decal electronics for printed high performance cmos electronic systems

    KAUST Repository

    Hussain, Muhammad Mustafa; Sevilla, Galo Torres; Cordero, Marlon Diaz; Kutbee, Arwa T.

    2017-01-01

    High performance complementary metal oxide semiconductor (CMOS) electronics are critical for any full-fledged electronic system. However, state-of-the-art CMOS electronics are rigid and bulky making them unusable for flexible electronic applications

  5. Electronic Publishing or Electronic Information Handling?

    Science.gov (United States)

    Heck, A.

    The current dramatic evolution in information technology is bringing major modifications in the way scientists communicate. The concept of 'electronic publishing' is too restrictive and has often different, sometimes conflicting, interpretations. It is thus giving way to the broader notion of 'electronic information handling' encompassing the diverse types of information, the different media, as well as the various communication methodologies and technologies. New problems and challenges result also from this new information culture, especially on legal, ethical, and educational grounds. The procedures for validating 'published material' and for evaluating scientific activities will have to be adjusted too. 'Fluid' information is becoming a common concept. Electronic publishing cannot be conceived without link to knowledge bases nor without intelligent information retrieval tools.

  6. Electron transfer in proteins

    DEFF Research Database (Denmark)

    Farver, O; Pecht, I

    1991-01-01

    Electron migration between and within proteins is one of the most prevalent forms of biological energy conversion processes. Electron transfer reactions take place between active centers such as transition metal ions or organic cofactors over considerable distances at fast rates and with remarkable...... specificity. The electron transfer is attained through weak electronic interaction between the active sites, so that considerable research efforts are centered on resolving the factors that control the rates of long-distance electron transfer reactions in proteins. These factors include (in addition......-containing proteins. These proteins serve almost exclusively in electron transfer reactions, and as it turns out, their metal coordination sites are endowed with properties uniquely optimized for their function....

  7. Electrons in Nanostructures

    DEFF Research Database (Denmark)

    Flindt, Christian

    2007-01-01

    in the possibilities o®ered by the quantum mechanical behavior of electrons when it comes to informa- tion processing. This branch of research is also concerned with fundamental questions in physics. Besides an introduction to the above-mentioned subjects, the thesis con- tains a number of contributions to the ¯elds...... of coherent electron manip- ulation and the statistical description of electron transport through nano- devices. The physics of the electrons are described with a combination of numerical methods, developed and applied in the thesis, and more analytical approaches, which are also discussed. The thesis......-based communication. The statistical description of electron transport through nanostructures is based on rate equations, and the primary contribution of the thesis in that respect is the development of a method that allows for the calculation of the distribution of electrons passing through a device. The method...

  8. Transition to electronic publishing

    Science.gov (United States)

    Bowning, Sam

    Previous communications have described some of the many changes that will occur in the next few months as AGU makes the transition to fully electronic publishing. With the advent of the new AGU electronic publishing system, manuscripts will be submitted, edited, reviewed, and published in electronic formats. This piece discusses how the electronic journals will differ from the print journals. Electronic publishing will require some adjustments to the ways we currently think about journals from our perspective of standard print versions. Visiting the Web site of AGU's Geochemistry, Geophysics, Geosystems (G-Cubed) is a great way to get familiar with the look and feel of electronic publishing. However, protocols, especially for citations of articles, are still evolving. Some of the biggest changes for users of AGU publications may be the lack of page numbers, the use of a unique identifier (DOI),and changes in citation style.

  9. Electron microscopy of surfaces

    International Nuclear Information System (INIS)

    Venables, J.A.

    1981-01-01

    Electron beam techniques used to study clean surfaces and surface processes on a microscopic scale are reviewed. Recent experimental examples and possible future developments are discussed. Special emphasis is given to (i) transmission diffraction and microscopy techniques, including atomic imaging; (ii) Auger microscopy on bulk and thin film samples; (iii) secondary electron microscopy, especially low energy secondaries for work-function imaging and photoelectron imaging; and (iv) reflection electron microscopy and diffraction. (orig.)

  10. New electronics stuff chemistry

    International Nuclear Information System (INIS)

    Byeon, Su Il

    2003-04-01

    The first part of this book is about equilibrium electrochemistry on electric thermo dynamic equilibrium state of electrochemistry, crystal defect of solid, thermodynamics on defect electron and election in semiconductor, Gawani potential, volta potential and equilibrium potential and thermodynamics application in Gawani battery. The second part deals with dynamic electrochemistry electrode reaction kinetics and corrosion potential in normal state, diffusion and transport of ion and electron and current impedance spectroscopy. It also mentions industrial electrochemistry and laboratory works in electronics chemistry course.

  11. Ceramic Electron Multiplier

    International Nuclear Information System (INIS)

    Comby, G.

    1996-01-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  12. Organizing the Electronic Century

    OpenAIRE

    Richard N. Langlois

    2007-01-01

    This paper's title is an echo of Alfred Chandler's (2001) chronicle of the electronics industry, Inventing the Electronic Century. The paper attempts (A) a general reinterpretation of the pattern of technological advance in (American) electronics over the twentieth century and (B) a somewhat revisionist account of the role of organization and institution in that advance. The paper stresses the complex effects of product architecture and intellectual property regime on industrial organization ...

  13. Introduction to printed electronics

    CERN Document Server

    Suganuma, Katsuaki

    2014-01-01

    This book describes in detail modern technologies for printed electronics, explaining how nanotechnology and modern printing technology are merging to revolutionize electronics fabrication of thin, lightweight, large, and inexpensive products. Readers will benefit from the explanations of materials, devices and circuits used to design and implement the latest applications of printed electronics, such as thin flexible OLED displays, organic solar cells, OLED lighting, smart wallpaper, sensors, logic, memory and more.

  14. Interoperability for electronic ID

    OpenAIRE

    Zygadlo, Zuzanna

    2009-01-01

    Electronic Business, including eBanking, eCommerce and eGovernmental services, is today based on a large variety of security solutions, comprising electronic IDs provided by a broad community of Public Key Infrastructure (PKI) vendors. Significant differences in implementations of those solutions introduce a problem of lack of interoperability in electronic business, which have not yet been resolved by standardization and interoperability initiatives based on existing PKI trust models. It i...

  15. TRANSIENT ELECTRONICS CATEGORIZATION

    Science.gov (United States)

    2017-08-24

    AFRL-RY-WP-TR-2017-0169 TRANSIENT ELECTRONICS CATEGORIZATION Dr. Burhan Bayraktaroglu Devices for Sensing Branch Aerospace Components & Subsystems...SUBTITLE TRANSIENT ELECTRONICS CATEGORIZATION 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S) Dr. Burhan...88ABW-2017-3747, Clearance Date 31 July 2017. Paper contains color. 14. ABSTRACT Transient electronics is an emerging technology area that lacks proper

  16. Introduction to electronics

    CERN Document Server

    Korneff, Theodore

    1966-01-01

    Introduction to Electronics focuses on the study of electronics and electronic devices. Composed of 14 chapters, the book starts with discussions on dc circuits, including resistance, voltmeter, ammeter, galvanometer, internal resistance, and positive and negative currents. This topic is followed by discussions on ac circuits, particularly addressing voltage and current, average power, resistive load, complex plane, and parallel circuits. Discussions also focus on filters and tuned circuits, diodes, and power supplies. Particularly given attention are the processes, diagrams, and analyses

  17. Modern electronic materials

    CERN Document Server

    Watkins, John B

    2013-01-01

    Modern Electronic Materials focuses on the development of electronic components. The book first discusses the history of electronic components, including early developments up to 1900, developments up to World War II, post-war developments, and a comparison of present microelectric techniques. The text takes a look at resistive materials. Topics include resistor requirements, basic properties, evaporated film resistors, thick film resistors, and special resistors. The text examines dielectric materials. Considerations include basic properties, evaporated dielectric materials, ceramic dielectri

  18. Electron-beam lithography

    International Nuclear Information System (INIS)

    Harriott, L.; Liddle, A.

    1997-01-01

    As part of a commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article describes the use of electron beams to write features on silicon wafers. Recent advances in electron beam lithography, as it is known, could enable this technology to be used for the mass manufacture of silicon chips. The validation of space-charge optimization and evaluation of printing techniques is underway. (UK)

  19. Electron beam lithography

    International Nuclear Information System (INIS)

    Harriott, L.; Liddle, A.

    1997-01-01

    As part of a commemorative series of articles to mark the hundredth anniversary of the discovery of the electron, this article describes the use of electron beams to write features on silicon wafers. Recent advances in electron beam lithography, as it is known, could enable this technology to be used for the mass manufacture of silicon chips. The validation of space-charge optimization and evaluation of printing techniques is underway. 5 figs

  20. Electron microscopy and diffraction

    International Nuclear Information System (INIS)

    Gjoennes, J.; Olsen, A.

    1986-01-01

    This report is a description of research activities and plans at the electron microscopy laboratorium, Physics Department, University of Oslo. Since the first electron microscope was installed in 1968, the research has covered inorganic structures, physical metallurgy, as well as theory of electron scattering and the development of methods in this field. The current plans involve efforts in the development of crystallographic and spectroscopic methods

  1. The Electronic Notebook Ontology

    OpenAIRE

    Chalk, Stuart

    2016-01-01

    Science is rapidly being brought into the electronic realm and electronic laboratory notebooks (ELN) are a big part of this activity. The representation of the scientific process in the context of an ELN is an important component to making the data recorded in ELNs semantically integrated. This presentation will outline initial developments of an Electronic Notebook Ontology (ENO) that will help tie together the ExptML ontology, HCLS Community Profile data descriptions, and the VIVO-ISF ontol...

  2. Electronics Environmental Benefits Calculator

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Electronics Environmental Benefits Calculator (EEBC) was developed to assist organizations in estimating the environmental benefits of greening their purchase,...

  3. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2007-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Each chapter ends with a set

  4. High-power electronics

    CERN Document Server

    Kapitsa, Petr Leonidovich

    1966-01-01

    High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

  5. The auroral electron accelerator

    International Nuclear Information System (INIS)

    Bryant, D.A.; Hall, D.S.

    1989-01-01

    A model of the auroral electron acceleration process is presented in which the electrons are accelerated resonantly by lower-hybrid waves. The essentially stochastic acceleration process is approximated for the purposes of computation by a deterministic model involving an empirically derived energy transfer function. The empirical function, which is consistent with all that is known of electron energization by lower-hybrid waves, allows many, possibly all, observed features of the electron distribution to be reproduced. It is suggested that the process occurs widely in both space and laboratory plasmas. (author)

  6. Analytical Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — The Titan 80-300 is a transmission electron microscope (TEM) equipped with spectroscopic detectors to allow chemical, elemental, and other analytical measurements to...

  7. Two electron Rydberg states

    International Nuclear Information System (INIS)

    Cooke, W.E.

    1981-01-01

    This paper addresses the study of two-electron Rydberg atoms. With Multichannel Quantum Defect Theory (MQDT), there is a technique for characterizing a spectra in terms of a small number of parameters. A survey of some important effects specific to two-electon Rydberg states, using primarily the alkaline earth atoms for examples, is made. The remainder of the paper deals with a discussion of the electron-electron interaction, including some of the basic points of MQDT. Energy exchange between two electrons is also addressed

  8. Fundamentals of electronics

    CERN Document Server

    Schubert, Thomas F

    2015-01-01

    This book, Electronic Devices and Circuit Application, is the first of four books of a larger work, Fundamentals of Electronics. It is comprised of four chapters describing the basic operation of each of the four fundamental building blocks of modern electronics: operational amplifiers, semiconductor diodes, bipolar junction transistors, and field effect transistors. Attention is focused on the reader obtaining a clear understanding of each of the devices when it is operated in equilibrium. Ideas fundamental to the study of electronic circuits are also developed in the book at a basic level to

  9. Electronic signal conditioning

    CERN Document Server

    NEWBY, BRUCE

    1994-01-01

    At technician level, brief references to signal conditioning crop up in a fragmented way in various textbooks, but there has been no single textbook, until now!More advanced texts do exist but they are more mathematical and presuppose a higher level of understanding of electronics and statistics. Electronic Signal Conditioning is designed for HNC/D students and City & Guilds Electronics Servicing 2240 Parts 2 & 3. It will also be useful for BTEC National, Advanced GNVQ, A-level electronics and introductory courses at degree level.

  10. Electronics pocket book

    CERN Document Server

    Parr, E A

    1981-01-01

    Electronics Pocket Book, Fourth Edition is a nonmathematical presentation of the many varied topics covered by electronics. The book tackles electron physics, electronic components (i.e. resistors, capacitors, and conductors), integrated circuits, and the principles of a.c. and d.c. amplifiers. The text also discusses oscillators, digital circuits, digital computers, and optoelectronics (i.e., sensors, emitters, and devices that utilize light). Communications (such as line and radio communications, transmitters, receivers, and digital techniques); the principles and examples of servosystems; a

  11. Electron beam welding

    International Nuclear Information System (INIS)

    Schwartz, M.M.

    1974-01-01

    Electron-beam equipment is considered along with fixed and mobile electron-beam guns, questions of weld environment, medium and nonvacuum welding, weld-joint designs, tooling, the economics of electron-beam job shops, aspects of safety, quality assurance, and repair. The application of the process in the case of individual materials is discussed, giving attention to aluminum, beryllium, copper, niobium, magnesium, molybdenum, tantalum, titanium, metal alloys, superalloys, and various types of steel. Mechanical-property test results are examined along with the areas of application of electron-beam welding

  12. Flying Electronic Warfare Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Provides NP-3D aircraft host platforms for Effectiveness of Navy Electronic Warfare Systems (ENEWS) Program antiship missile (ASM) seeker simulators used...

  13. Free electron laser

    International Nuclear Information System (INIS)

    Ortega, J.M.; Billardon, M.

    1986-01-01

    Operation principle of a laser and an oscillator are recalled together with the klystron one. In the free electron laser, electrons go through an undulator or an optical klystron. Principles of the last one are given. The two distinct ways of producing coherent radiation with an undulator and an optical klystron are presented. The first one is the use of the free electron laser, the second is to make use of the spontaneous emission generation (harmonics generation). The different current types of free electron lasers are presented (Stanford, Los Alamos, Aco at Orsay). Prospects and applications are given in conclusion [fr

  14. Electronic circuits fundamentals & applications

    CERN Document Server

    Tooley, Mike

    2015-01-01

    Electronics explained in one volume, using both theoretical and practical applications.New chapter on Raspberry PiCompanion website contains free electronic tools to aid learning for students and a question bank for lecturersPractical investigations and questions within each chapter help reinforce learning Mike Tooley provides all the information required to get to grips with the fundamentals of electronics, detailing the underpinning knowledge necessary to appreciate the operation of a wide range of electronic circuits, including amplifiers, logic circuits, power supplies and oscillators. The

  15. Flexible Electronics Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Flexible Electronics Research Facility designs, synthesizes, tests, and fabricates materials and devices compatible with flexible substrates for Army information...

  16. Electronics circuits and systems

    CERN Document Server

    Bishop, Owen

    2011-01-01

    The material in Electronics - Circuits and Systems is a truly up-to-date textbook, with coverage carefully matched to the electronics units of the 2007 BTEC National Engineering and the latest AS and A Level specifications in Electronics from AQA, OCR and WJEC. The material has been organized with a logical learning progression, making it ideal for a wide range of pre-degree courses in electronics. The approach is student-centred and includes: numerous examples and activities; web research topics; Self Test features, highlighted key facts, formulae and definitions. Ea

  17. Electrons in water radiolysis

    International Nuclear Information System (INIS)

    Laverne, J.A.; Pimblott, S.M.

    2006-01-01

    The hydrated electron is the main reducing species produced in the radiolysis of water. Many studies have examined its reactivity using pulsed radiolysis techniques and competition kinetics. Data bases list hundreds of rate coefficients for reaction of the hydrated electron with substances ranging from inorganic ions like nitrate to biopolymers like DNA. Although the chemistry of the hydrated electron is often examined, its mechanism of formation and variation in yield are considerable less known, especially under extreme conditions such as in high temperature water or with heavy ion radiolysis. This work will examine various aspects of the radiation chemistry of the hydrated electron beginning with the generation of secondary electrons in primary energy loss events during the passage of ionizing radiation to the radiolytic yields of the hydrated electron produced by different types of radiation. Ion radiation is a 'white light source.' Energy losses range from the minimum excitation energy of the medium up to the kinematic maximum determined by the collision parameters. However, certain energy loss events are more probable than others. The dipole oscillator strength distributions of media essentially give the probability of energy loss events in collisions with no momentum transfer. Dipole oscillator distributions have been constructed from experimental data for a wide variety of materials including all the phases of water. Calculations using cross sections based on dipole oscillator distributions show that the most probable energy loss event in water is only about 20 eV with an average value closer to 60 eV. The preponderance of energy loss events of less than 100 eV means that many low energy electrons are formed by the passage of a single ion. Low energy electrons have short mean free paths and they remain in the vicinity of the primary energy loss events. The spatial distribution of these low energy electrons defines the radial track structure of the incident

  18. INDRA. Electronic Architecture

    International Nuclear Information System (INIS)

    Ganil Team.

    1993-01-01

    The INDRA multidetector electronics is described. The system is a set of 17 rings consisting of 96 ionization chambers and 180 silicon detectors plus 324 cesium iodide and 12 Phoswich scintillators. Their integrated electronic lines, the trigger modules, the control and data acquisition units are presented briefly. (R.P.) 6 figs

  19. Recycling of electronic scrap

    DEFF Research Database (Denmark)

    Legarth, Jens Brøbech

    This Ph.D. thesis deals with the growingly important field of electronics recycling with special attention to the problem of printed circuit board recycling. A literature survey of contemporary electronics recycling and printed circuit board recycling is presented.Further, an analysis of the role...

  20. Cooling of electronic equipment

    DEFF Research Database (Denmark)

    A. Kristensen, Anders Schmidt

    2003-01-01

    Cooling of electronic equipment is studied. The design size of electronic equipment decrease causing the thermal density to increase. This affect the cooling which can cause for example failures of critical components due to overheating or thermal induced stresses. Initially a pin fin heat sink...

  1. Scanning electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cox, B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    1970-05-15

    The JSM-11 scanning electron microscope at CRNL has been used extensively for topographical studies of oxidized metals, fracture surfaces, entomological and biological specimens. A non-dispersive X-ray attachment permits the microanalysis of the surface features. Techniques for the production of electron channeling patterns have been developed. (author)

  2. Electron scattering from tetrahydrofuran

    International Nuclear Information System (INIS)

    Fuss, M C; Sanz, A G; García, G; Muñoz, A; Oller, J C; Blanco, F; Do, T P T; Brunger, M J; Almeida, D; Limão-Vieira, P

    2012-01-01

    Electron scattering from Tetrahydrofuran (C 4 H 8 O) was investigated over a wide range of energies. Following a mixed experimental and theoretical approach, total scattering, elastic scattering and ionization cross sections as well as electron energy loss distributions were obtained.

  3. Paradoxes of unstable electron

    International Nuclear Information System (INIS)

    Okun, L.B.; Zeldovich, Ya.B.

    1978-01-01

    The hypothesis that electron is unstable - when it is consistent with the vanishing mass of the photon- leads to a number of paradoxical statements. The lifetime of the electron is determined by emission of a huge number of longitudinal photons and exponentially depends on the amount of emitted energy. This suggests to discuss searches for charge nonconservation in experiments with high energy particles

  4. Electron scattering violates parity

    CERN Multimedia

    2004-01-01

    Parity violation has been observed in collisions between electrons at the Stanford Linear Accelerator Center (SLAC) in the US. The resuls, which are in agreement with the Stanford Model of particle physics, also provide a new measurement of the weak charge of the electron (½ page)

  5. Electronically Controlled Resistor Bank

    Science.gov (United States)

    Ross, Walter L.

    1987-01-01

    Resistance quickly varied in small steps over wide range. Device with no moving parts provides variable electrical resistance. Used with analog or digital circuity to provide electronic selection of large number of resistance values for testing, simulation, control, or other purposes. Nearest electromechanical equivalent of all-electronic device is potentiometer driven by servomotor.

  6. Voltmeter with Compton electrons

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, N R; Gorbics, S G; Weidenheimer, D M [Berkeley Research Associates, Springfield, VA (United States)

    1997-12-31

    A technique to measure the electron end point energy of bremsstrahlung in the MV regime using only two detectors is described. One of the detector measures the total radiation, the other filters out all except the hardest photons by looking only at their Compton electrons, whose average energy is determined with a magnetic field. (author). 4 figs., 2 refs.

  7. Advances in Opto Electronics

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Advances in Opto Electronics. Optoelectronics is where electronics was 15 years back. All Optical Amplifiers and Semiconductor Amplifiers. Fastest Semiconductor (InP) switch is at 170GHz- where is terrabit ? MEMS based switches that route traffic at wavelength level ...

  8. Electron beam welding

    International Nuclear Information System (INIS)

    Gabbay, M.

    1972-01-01

    The bead characteristics and the possible mechanisms of the electron beam penetration are presented. The different welding techniques are exposed and the main parts of an electron beam welding equipment are described. Some applications to nuclear, spatial and other industries are cited [fr

  9. Electron beam simulation applicators

    International Nuclear Information System (INIS)

    Purdy, J.A.

    1983-01-01

    A system for simulating electron beam treatment portals using low-temperature melting point alloy is described. Special frames having the same physical dimensions as the electron beam applicators used on the Varian Clinac 20 linear accelerator were designed and constructed

  10. Radiative electron capture

    International Nuclear Information System (INIS)

    Biggerstaff, J.A.; Appleton, B.R.; Datz, S.; Moak, C.D.; Neelavathi, V.N.; Noggle, T.S.; Ritchie, R.H.; VerBeek, H.

    1975-01-01

    Some data are presented for radiative electron capture by fast moving ions. The radiative electron capture spectrum is shown for O 8+ in Ag, along with the energy dependence of the capture cross-section. A discrepancy between earlier data, theoretical prediction, and the present data is pointed out. (3 figs) (U.S.)

  11. Electronics and Lithuanian Terminology

    Directory of Open Access Journals (Sweden)

    Stasys Zajankauskas

    2011-04-01

    Full Text Available It is found that the vacuum triode, transistor, monolithic circuit and microprocessor were the most important inventions of traditional electronics. Thus, the origins of the traditional electronics should be associated with the invention of the vacuum triode, but not with the invention of vacuum diode. It is shown that the science of electronics is not as young as computer science or up-to-date information technologies: electronics, including active electronics, had already celebrated the centenary, and the period of 2004–2008 is the period of numerous already solid jubilees. Thus, the terminology of electronics is not at initial stage of evolution as well – general terms should be already systematized and normalized. However, Lithuanian terms for electronic devices invented before tens of years and terms for old-defined notions associated with these devices are still varying, some are worsened. Especially, the incorrectly motivated terms used for variations of transistors and microcircuits are analyzed in the article. It is motivated which terms are preferable, systematic and exact. The paper is dedicated to the 50th anniversary of monolithic circuit, as well as the 60th anniversary of transistor, the 40th jubilee of microprocessor and centenary of electronics.

  12. Electron tunneling in chemistry

    International Nuclear Information System (INIS)

    Zamaraev, K.I.; Khajrutdinov, R.F.; Zhdanov, V.P.; Molin, Yu.N.

    1985-01-01

    Results of experimental and theoretical investigations are outlined systematically on electron tunnelling in chemical reactions. Mechanism of electron transport to great distances is shown to be characteristic to chemical compounds of a wide range. The function of tunnel reactions is discussed for various fields of chemistry, including radiation chemistry, electrochemistry, chemistry of solids, chemistry of surface and catalysis

  13. Managing electronic records

    CERN Document Server

    McLeod, Julie

    2005-01-01

    For records management courses, this book covers the theory and practice of managing electronic records as business and information assets. It focuses on the strategies, systems and procedures necessary to ensure that electronic records are appropriately created, captured, organized and retained over time to meet business and legal requirements.

  14. ELECTRON COOLING FOR RHIC

    International Nuclear Information System (INIS)

    BEN-ZVI, I.; AHRENS, L.; BRENNAN, M.; HARRISON, M.; KEWISCH, J.; MACKAY, W.; PEGGS, S.; ROSER, T.; SATOGATA, T.; TRBOJEVIC, D.; YAKIMENKO, V.

    2001-01-01

    We introduce plans for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This project has a number of new features as electron coolers go: It will cool 100 GeV/nucleon ions with 50 MeV electrons; it will be the first attempt to cool a collider at storage-energy; and it will be the first cooler to use a bunched beam and a linear accelerator as the electron source. The linac will be superconducting with energy recovery. The electron source will be based on a photocathode gun. The project is carried out by the Collider-Accelerator Department at BNL in collaboration with the Budker Institute of Nuclear Physics

  15. Electron - proton colliders

    International Nuclear Information System (INIS)

    Wiik, B.H.

    1985-01-01

    Electron-proton storage rings allow us to study the interaction between the two basic constituents of matter, electrons and quarks at very short distances. Such machines were first discussed in connection with the ISR but the idea was abandoned because of the anticipated low counting rate. The interest in electron-proton storage rings was rekindeled by the discovery of large pointlike cross sections in lepton-hardon interactions and several/sup 2-15/ projects have been discussed during the past decade. However, despite a glorious past, which includes the discovery of quarks and neutral currents, and a multitude of proposals no electron-proton storage ring has ever been built. What we might learn by studying electron-proton collisions at high energies is discussed. After some brief comments on present proposals the proposed DESY ep project HERA is described as an example of how to realize such a machine

  16. Electron: Cluster interactions

    International Nuclear Information System (INIS)

    Scheidemann, A.A.; Knight, W.D.

    1994-02-01

    Beam depletion spectroscopy has been used to measure absolute total inelastic electron-sodium cluster collision cross sections in the energy range from E ∼ 0.1 to E ∼ 6 eV. The investigation focused on the closed shell clusters Na 8 , Na 20 , Na 40 . The measured cross sections show an increase for the lowest collision energies where electron attachment is the primary scattering channel. The electron attachment cross section can be understood in terms of Langevin scattering, connecting this measurement with the polarizability of the cluster. For energies above the dissociation energy the measured electron-cluster cross section is energy independent, thus defining an electron-cluster interaction range. This interaction range increases with the cluster size

  17. Practical electronics for inventors

    CERN Document Server

    Scherz, Paul

    2013-01-01

    Spark your creativity and gain the electronics skills required to transform your innovative ideas into functioning gadgets. This hands-on, updated guide outlines electrical principles and provides thorough, easy-to-follow instructions, schematics, and illustrations. Findout how to select components, safely assemble circuits, perform error tests, and build plug-and-play prototypes. Practical Electronics for Inventors, Third Edition, features all-new chapters on sensors, microcontrollers, modular electronics, and the latest software tools. Coverage includes: Resistors, capacitors, inductors, and transformers Diodes, transistors, and integrated circuits Optoelectronics, solar cells, and phototransistors Sensors, GPS modules, and touch screens Op amps, regulators, and power supplies Digital electronics, LCD displays, and logic gates Microcontrollers and prototyping platforms, including Arduino DC motors, RC servos, and stepper motors Microphones, audio amps, and speakers Modular electronics and prototyping.

  18. Genetic diversity of Claviceps africana on sorghum and Hyparrhenia

    Czech Academy of Sciences Publication Activity Database

    Pažoutová, Sylvie; Frederickson, D.E.

    2005-01-01

    Roč. 54, - (2005), s. 749-763 ISSN 0032-0862 Institutional research plan: CEZ:AV0Z5020903 Keywords : cerebella andropogonis * claviceps spp. * clonality Subject RIV: EE - Microbiology, Virology Impact factor: 1.718, year: 2005

  19. Larvicidal properties of simalikalactone d from Quassia africana ...

    African Journals Online (AJOL)

    The root extract was partitioned into hexane, chloroform and ethyl acetate and the resulting extracts screened for larvicidal properties. The extracts and the fraction with the highest bioactivity were subjected to repeated column chromatography and isolated compounds evaluated for potential toxicity to An. gambiae larvae.

  20. THE EFFECT OF (Treculia Africana) AFRICAN BREADFRUIT ON ...

    African Journals Online (AJOL)

    DJFLEX

    equilibrium between the intracellular compartment. Potassium is vital to homeostasis. The major force maintaining the difference in cation concentration between the intracellular fluid and the extra cellular fluid is the activity of sodium potassium pump intergral to all cell membrane (Field et al 2006) this may explain the.

  1. Physico-chemical and toxicological studies on Afzelia africana seed ...

    African Journals Online (AJOL)

    USER

    2010-03-29

    Mar 29, 2010 ... value, saponification value, specific gravity, free fatty acid and refractive index of ... mg/100 g of oxalate, 0.70 mg/kg of phytate and neither tannins or cyanogenic glycosides. ..... Studies on the levels of oxalic and phytic acid in.

  2. A chapter of early medical africana | Norwich | South African Medical ...

    African Journals Online (AJOL)

    Reference is also made to an interestino original medical volume to which Ten Rhyne contributed the use of acupuncture and scarification for the treatment of podagra (gout). A description of the physical methods used by the Hottentots of that period is illustrated from original engravings contained in the famous Kolbe ...

  3. Preliminary study on the antioxidant effect of Kigelia africana fruit ...

    African Journals Online (AJOL)

    USER

    2010-03-01

    Mar 1, 2010 ... systemic challenges can lead to an antioxidant/pro-oxidant disequilibrium. .... dithiobisnitro benzoic acid (DTNB) in 100 ml of 0.1% sodium nitrate) and 3.0 ml ..... mice: Effects of some medicinal plants on the oxidative defence.

  4. Electronically cloaked nanoparticles

    Science.gov (United States)

    Shen, Wenqing

    The concept of electronic cloaking is to design objects invisible to conduction electrons. The approach of electronic cloaking has been recently suggested to design invisible nanoparticle dopants with electronic scattering cross section smaller than 1% of the physical cross section (pi a2), and therefore to enhance the carrier mobility of bulk materials. The proposed nanoparticles have core-shell structures. The dopants are incorporated inside the core, while the shell layer serves both as a spacer to separate the charge carriers from their parent atoms and as a cloaking shell to minimize the scattering cross section of the electrons from the ionized nanoparticles. Thermoelectric materials are usually highly doped to have enough carrier density. Using invisible dopants could achieve larger thermoelectric power factors by enhancing the electronic mobility. Core-shell nanoparticles show an advantage over one-layer nanoparticles, which are proposed in three-dimensional modulation doping. However designing such nanoparticles is not easy as there are too many parameters to be considered. This thesis first shows an approach to design hollow nanoparticles by applying constrains on variables. In the second part, a simple mapping approach is introduced where one can identify possible core-shell particles by comparing the dimensionless parameters of chosen materials with provided maps. In both parts of this work, several designs with realistic materials were made and proven to achieve electronic cloaking. Improvement in the thermoelectric power factor compared to the traditional impurity doping method was demonstrated in several cases.

  5. Electron Cooling of RHIC

    CERN Document Server

    Ben-Zvi, Ilan; Barton, Donald; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Bruhwiler, David L; Burger, Al; Burov, Alexey; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Derbenev, Yaroslav S; Eidelman, Yury I; Favale, Anthony; Fedotov, Alexei V; Fischer, Wolfram; Funk, L W; Gassner, David M; Hahn, Harald; Harrison, Michael; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Koop, Ivan; Lambiase, Robert; Litvinenko, Vladimir N; MacKay, William W; Mahler, George; Malitsky, Nikolay; McIntyre, Gary; Meng, Wuzheng; Merminga, Lia; Meshkov, Igor; Mirabella, Kerry; Montag, Christoph; Nagaitsev, Sergei; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Parkhomchuk, Vasily; Parzen, George; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Sekutowicz, Jacek; Shatunov, Yuri; Sidorin, Anatoly O; Skrinsky, Aleksander Nikolayevich; Smirnov, Alexander V; Smith, Kevin T; Todd, Alan M M; Trbojevic, Dejan; Troubnikov, Grigory; Wang, Gang; Wei, Jie; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Zaltsman, Alex; Zhao, Yongxiang; ain, Animesh K

    2005-01-01

    We report progress on the R&D program for electron-cooling of the Relativistic Heavy Ion Collider (RHIC). This electron cooler is designed to cool 100 GeV/nucleon at storage energy using 54 MeV electrons. The electron source will be a superconducting RF photocathode gun. The accelerator will be a superconducting energy recovery linac. The frequency of the accelerator is set at 703.75 MHz. The maximum electron bunch frequency is 9.38 MHz, with bunch charge of 20 nC. The R&D program has the following components: The photoinjector and its photocathode, the superconducting linac cavity, start-to-end beam dynamics with magnetized electrons, electron cooling calculations including benchmarking experiments and development of a large superconducting solenoid. The photoinjector and linac cavity are being incorporated into an energy recovery linac aimed at demonstrating ampere class current at about 20 MeV. A Zeroth Order Design Report is in an advanced draft state, and can be found on the web at http://www.ags...

  6. Coherent electron cooling

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko,V.

    2009-05-04

    Cooling intense high-energy hadron beams remains a major challenge in modern accelerator physics. Synchrotron radiation is still too feeble, while the efficiency of two other cooling methods, stochastic and electron, falls rapidly either at high bunch intensities (i.e. stochastic of protons) or at high energies (e-cooling). In this talk a specific scheme of a unique cooling technique, Coherent Electron Cooling, will be discussed. The idea of coherent electron cooling using electron beam instabilities was suggested by Derbenev in the early 1980s, but the scheme presented in this talk, with cooling times under an hour for 7 TeV protons in the LHC, would be possible only with present-day accelerator technology. This talk will discuss the principles and the main limitations of the Coherent Electron Cooling process. The talk will describe the main system components, based on a high-gain free electron laser driven by an energy recovery linac, and will present some numerical examples for ions and protons in RHIC and the LHC and for electron-hadron options for these colliders. BNL plans a demonstration of the idea in the near future.

  7. Dose calculation for electrons

    International Nuclear Information System (INIS)

    Hirayama, Hideo

    1995-01-01

    The joint working group of ICRP/ICRU is advancing the works of reviewing the ICRP publication 51 by investigating the data related to radiation protection. In order to introduce the 1990 recommendation, it has been demanded to carry out calculation for neutrons, photons and electrons. As for electrons, EURADOS WG4 (Numerical Dosimetry) rearranged the data to be calculated at the meeting held in PTB Braunschweig in June, 1992, and the question and request were presented by Dr. J.L. Chartier, the responsible person, to the researchers who are likely to undertake electron transport Monte Carlo calculation. The author also has carried out the requested calculation as it was the good chance to do the mutual comparison among various computation codes regarding electron transport calculation. The content that the WG requested to calculate was the absorbed dose at depth d mm when parallel electron beam enters at angle α into flat plate phantoms of PMMA, water and ICRU4-element tissue, which were placed in vacuum. The calculation was carried out by the versatile electron-photon shower computation Monte Carlo code, EGS4. As the results, depth dose curves and the dependence of absorbed dose on electron energy, incident angle and material are reported. The subjects to be investigated are pointed out. (K.I.)

  8. Polarized electron sources

    International Nuclear Information System (INIS)

    Prepost, R.

    1994-01-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented

  9. Electronic devices and circuits

    CERN Document Server

    Pridham, Gordon John

    1968-01-01

    Electronic Devices and Circuits, Volume 1 deals with the design and applications of electronic devices and circuits such as passive components, diodes, triodes and transistors, rectification and power supplies, amplifying circuits, electronic instruments, and oscillators. These topics are supported with introductory network theory and physics. This volume is comprised of nine chapters and begins by explaining the operation of resistive, inductive, and capacitive elements in direct and alternating current circuits. The theory for some of the expressions quoted in later chapters is presented. Th

  10. Electron collisions with biomolecules

    International Nuclear Information System (INIS)

    McKoy, V; Winstead, C

    2008-01-01

    We report on results of recent studies of collisions of low-energy electrons with nucleobases and other DNA constituents. A particular focus of these studies has been the identification and characterization of resonances that play a role in electron attachment leading to strand breaks in DNA. Comparison of the calculated resonance positions with results of electron transmission measurements is quite encouraging. However, the higher-lying π* resonances of the nucleobases appear to be of mixed elastic and core-excited character. Such resonant channel coupling raises the interesting possibility that the higher π*resonances in the nucleobases may promote dissociation of DNA by providing doorway states to triplet excited states.

  11. Field emission electronics

    CERN Document Server

    Egorov, Nikolay

    2017-01-01

    This book is dedicated to field emission electronics, a promising field at the interface between “classic” vacuum electronics and nanotechnology. In addition to theoretical models, it includes detailed descriptions of experimental and research techniques and production technologies for different types of field emitters based on various construction principles. It particularly focuses on research into and production of field cathodes and electron guns using recently developed nanomaterials and carbon nanotubes. Further, it discusses the applications of field emission cathodes in new technologies such as light sources, flat screens, microwave and X-ray devices.

  12. Quantum electronics basic theory

    CERN Document Server

    Fain, V M; Sanders, J H

    1969-01-01

    Quantum Electronics, Volume 1: Basic Theory is a condensed and generalized description of the many research and rapid progress done on the subject. It is translated from the Russian language. The volume describes the basic theory of quantum electronics, and shows how the concepts and equations followed in quantum electronics arise from the basic principles of theoretical physics. The book then briefly discusses the interaction of an electromagnetic field with matter. The text also covers the quantum theory of relaxation process when a quantum system approaches an equilibrium state, and explai

  13. Power Electronics for Microgrids

    DEFF Research Database (Denmark)

    Dragicevic, Tomislav; Blaabjerg, Frede

    2016-01-01

    A microgrid (MG) is a stand-alone or grid-connected hybrid renewable system that uses distributed renewable and nonrenewable energy sources and energy storage systems (ESSs) to supply power to local loads. The system is ordinarily based on power electronics, with interface converters allowing...... a continuous supply of power in the presence of variable RES production. This chapter describes some specific features of DC MGs in terms of power architecture, control, and protection. It also reviews several uncommon power electronic interfaces. Regarding control, operation without critical communication...... are explained in this chapter. The chapter concludes with a review of power electronic intensive protection solutions for DC MGs....

  14. Polarized electron sources

    Energy Technology Data Exchange (ETDEWEB)

    Prepost, R. [Univ. of Wisconsin, Madison, WI (United States)

    1994-12-01

    The fundamentals of polarized electron sources are described with particular application to the Stanford Linear Accelerator Center. The SLAC polarized electron source is based on the principle of polarized photoemission from Gallium Arsenide. Recent developments using epitaxially grown, strained Gallium Arsenide cathodes have made it possible to obtain electron polarization significantly in excess of the conventional 50% polarization limit. The basic principles for Gallium and Arsenide polarized photoemitters are reviewed, and the extension of the basic technique to strained cathode structures is described. Results from laboratory measurements of strained photocathodes as well as operational results from the SLAC polarized source are presented.

  15. BEPCII electronic logbook system

    International Nuclear Information System (INIS)

    Liu Shu; Zhao Jijiu; Wang Chunhong

    2007-01-01

    According to demands of BEPCII construction and future operation, we are going to supply an open electronic logbook platform for people to record their message in developing and running BEPCII, and browse the log-book on website. That gives people an open and transparent logbook, rather than traditional paper notebook. With the template of DESY's Elogbook, the BEPCII electronic logbook was developed, using the popular JSP technology to develop dynamic Web applications. This paper will introduce the development of BEPCII electronic logbook system. (authors)

  16. Electronic components and systems

    CERN Document Server

    Dennis, W H

    2013-01-01

    Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn

  17. A simple electron multiplexer

    International Nuclear Information System (INIS)

    Dobrzynski, L; Akjouj, A; Djafari-Rouhani, B; Al-Wahsh, H; Zielinski, P

    2003-01-01

    We present a simple multiplexing device made of two atomic chains coupled by two other transition metal atoms. We show that this simple atomic device can transfer electrons at a given energy from one wire to the other, leaving all other electron states unaffected. Closed-form relations between the transmission coefficients and the inter-atomic distances are given to optimize the desired directional electron ejection. Such devices can be adsorbed on insulating substrates and characterized by current surface technologies. (letter to the editor)

  18. Electron paramagnetic resonance

    CERN Document Server

    Al'tshuler, S A

    2013-01-01

    Electron Paramagnetic Resonance is a comprehensive text on the field of electron paramagnetic resonance, covering both the theoretical background and the results of experiment. This book is composed of eight chapters that cover theoretical materials and experimental data on ionic crystals, since these are the materials that have been most extensively studied by the methods of paramagnetic resonance. The opening chapters provide an introduction to the basic principles of electron paramagnetic resonance and the methods of its measurement. The next chapters are devoted to the theory of spectra an

  19. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B

    1972-01-01

    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  20. Auger electron spectroscopy

    International Nuclear Information System (INIS)

    Gopalaraman, C.P.

    1975-01-01

    General features of electron excited Auger electron spectroscopy (AES) which is a nondestructive technique for the analysis of surfaces upto about 15 Adeg depth with a detection limit of about 0.1% of a monolayer. Methods of measuring the Auger electron energies and recent improvements in the instrumentation are reviewed. Typical energy resolution is found to be about 0.5% which is specially suited for the detection of light elements. It is widely used in metallurgy, surface chemistry and thin film studies. (K.B.)

  1. Modern dictionary of electronics

    CERN Document Server

    Graf, Rudolf F

    1999-01-01

    Included in this fully revised classic are well over 28,000 terms, phrases, acronyms, and abbreviations from the ever-expanding worlds of consumer electronics, optics, microelectronics, computers, communications, and medical electronics. From the basic elements of theory to the most cutting-edge circuit technology, this book explains it all in both words and pictures.For easy reference, the author has provided definitions for standard abbreviations and equations as well as tables of SI (International System of Units) units, measurements, and schematic symbolsModern Dictionary of Electronics is

  2. VLSI electronics microstructure science

    CERN Document Server

    1982-01-01

    VLSI Electronics: Microstructure Science, Volume 4 reviews trends for the future of very large scale integration (VLSI) electronics and the scientific base that supports its development.This book discusses the silicon-on-insulator for VLSI and VHSIC, X-ray lithography, and transient response of electron transport in GaAs using the Monte Carlo method. The technology and manufacturing of high-density magnetic-bubble memories, metallic superlattices, challenge of education for VLSI, and impact of VLSI on medical signal processing are also elaborated. This text likewise covers the impact of VLSI t

  3. Single Electron Tunneling

    International Nuclear Information System (INIS)

    Ruggiero, Steven T.

    2005-01-01

    Financial support for this project has led to advances in the science of single-electron phenomena. Our group reported the first observation of the so-called ''Coulomb Staircase'', which was produced by tunneling into ultra-small metal particles. This work showed well-defined tunneling voltage steps of width e/C and height e/RC, demonstrating tunneling quantized on the single-electron level. This work was published in a now well-cited Physical Review Letter. Single-electron physics is now a major sub-field of condensed-matter physics, and fundamental work in the area continues to be conducted by tunneling in ultra-small metal particles. In addition, there are now single-electron transistors that add a controlling gate to modulate the charge on ultra-small photolithographically defined capacitive elements. Single-electron transistors are now at the heart of at least one experimental quantum-computer element, and single-electron transistor pumps may soon be used to define fundamental quantities such as the farad (capacitance) and the ampere (current). Novel computer technology based on single-electron quantum dots is also being developed. In related work, our group played the leading role in the explanation of experimental results observed during the initial phases of tunneling experiments with the high-temperature superconductors. When so-called ''multiple-gap'' tunneling was reported, the phenomenon was correctly identified by our group as single-electron tunneling in small grains in the material. The main focus throughout this project has been to explore single electron phenomena both in traditional tunneling formats of the type metal/insulator/particles/insulator/metal and using scanning tunneling microscopy to probe few-particle systems. This has been done under varying conditions of temperature, applied magnetic field, and with different materials systems. These have included metals, semi-metals, and superconductors. Amongst a number of results, we have

  4. Consulting in Electronic Commerce

    Directory of Open Access Journals (Sweden)

    Florentina Loredana Tache

    2010-10-01

    Full Text Available Economic development of electronic services provide advice and many agents of existingreferral systems to recommend and provide products, information and customized views of thecommunity through a personalized interaction in real time. Distributed systems of autonomous agentsare becoming increasingly important in electronic comet because the basic decisions of agents adviceon trust and reputation are taken in a similar way human society. If these decisions will be as a realconsumer protection, when new aspects of online consumer legislation will become usefulinformation in advice and consulting of electronic commerce.

  5. Coding for Electronic Mail

    Science.gov (United States)

    Rice, R. F.; Lee, J. J.

    1986-01-01

    Scheme for coding facsimile messages promises to reduce data transmission requirements to one-tenth current level. Coding scheme paves way for true electronic mail in which handwritten, typed, or printed messages or diagrams sent virtually instantaneously - between buildings or between continents. Scheme, called Universal System for Efficient Electronic Mail (USEEM), uses unsupervised character recognition and adaptive noiseless coding of text. Image quality of resulting delivered messages improved over messages transmitted by conventional coding. Coding scheme compatible with direct-entry electronic mail as well as facsimile reproduction. Text transmitted in this scheme automatically translated to word-processor form.

  6. The art of electronics

    CERN Document Server

    Horowitz, Paul

    2015-01-01

    At long last, here is the thoroughly revised and updated third edition of the hugely successful Art of Electronics. It is widely accepted as the best single authoritative book on electronic circuit design. In addition to new or enhanced coverage of many topics, the Third Edition includes: 90 oscilloscope screenshots illustrating the behavior of working circuits; dozens of graphs giving highly useful measured data of the sort that's often buried or omitted in datasheets but which you need when designing circuits; 80 tables (listing some 1650 active components), enabling intelligent choice of circuit components by listing essential characteristics (both specified and measured) of available parts. The new Art of Electronics ​​retains the feeling of informality and easy access that helped make the earlier editions so successful and popular. It is an indispensable reference and the gold standard​​ for anyone, student or researcher, professional or amateur, who works with electronic circuits.

  7. Electron and Photon ID

    CERN Document Server

    Hryn'ova, Tetiana; The ATLAS collaboration

    2017-01-01

    The identification of prompt photons and the rejection of background coming mostly from photons from hadron decays relies on the high granularity of the ATLAS calorimeter. The electron identification used in ATLAS for run 2 is based on a likelihood discrimination to separate isolated electron candidates from candidates originating from photon conversions, hadron misidentification and heavy flavor decays. In addition, isolation variables are used as further handles to separate signal and background. Several methods are used to measure with data the efficiency of the photon identification requirements, to cover a broad energy spectrum. At low energy, photons from radiative Z decays are used. In the medium energy range, similarities between electrons and photon showers are exploited using Z->ee decays. At high energy, inclusive photon samples are used. The measurement of the efficiencies of the electron identification and isolation cuts are performed with the data using tag and probe techniques with large statis...

  8. Channel electron multipliers

    International Nuclear Information System (INIS)

    Seidman, A.; Avrahami, Z.; Sheinfux, B.; Grinberg, J.

    1976-01-01

    A channel electron multiplier is described having a tubular wall coated with a secondary-electron emitting material and including an electric field for accelerating the electrons, the electric field comprising a plurality of low-resistive conductive rings each alternating with a high-resistive insulating ring. The thickness of the low-resistive rings is many times larger than that of the high-resistive rings, being in the order of tens of microns for the low-resistive rings and at least one order of magnitude lower for the high-resistive rings; and the diameter of the channel tubular walls is also many times larger than the thickness of the high-resistive rings. Both single-channel and multiple-channel electron multipliers are described. A very important advantage, particularly in making multiple-channel multipliers, is the simplicity of the procedure that may be used in constructing such multipliers. Other operational advantages are described

  9. Typewriting by Electronics

    Science.gov (United States)

    Etier, Faborn

    1971-01-01

    By using the electronic typewriting teaching aid, it is believed by those closely associated with its use in teaching typing that as much can be accomplished in one semester as in two semesters using the conventional method of teaching. (Editor)

  10. Electron identification at CDF

    International Nuclear Information System (INIS)

    Kim, Shinhong

    1990-01-01

    Electron identification at CDF is performed using the information of lateral and longitudinal shower spread, the track-cluster position match and the energy-momentum match. The tracking chamber with a solenoidal magnetic field at CDF is powerful for rejecting the backgrounds such as the π ± - π 0 overlaps, the π 0 /γ conversions and interactive π ± in electromagnetic calorimeter: The energy- momentum match cut can decrease the background due to the π ± - π 0 overlaps for non-isolated electrons with Et above 10 GeV by a factor of 20. The conversion electrons are identified using track information with an efficiency of 80 ± 3%. The charge of electrons from W decay can be determined in the pseudorapidity range of |η| < 1.7 at CDF. The charge determination is useful for background estimation of Drell-Yan physics and heavy flavor physics. 5 refs., 5 figs

  11. The electron accelerator Ridgetron

    International Nuclear Information System (INIS)

    Hayashizaki, N.; Hattori, T.; Odera, M.; Fujisawa, T.

    1999-01-01

    Many electron accelerators of DC or RF type have been widely used for electron beam irradiation (curing, crosslinking of polymers, sterilization of medical disposables, preservation of food, etc.). Regardless of the acceleration energy, the accelerators to be installed in industrial facilities, have to satisfy the requires of compact size, low power consumption and stable operation. The DC accelerator is realized very compact in the energy under 300 keV, however, it is large to prevent the discharge of an acceleration column in the energy over 300 keV. The RF electron accelerator Ridgetron has been developed to accelerate the continuous beam of the 0.5-10 MeV range in compact space. It is the first example as an electron accelerator incorporated a ridged RF cavity. A prototype system of final energy of 2.5 MeV has been studied to confirm the feasibility at present

  12. Advanced Electron Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Siemann, R.

    2005-02-14

    The research into advanced acceleration concepts for electron linear accelerators being pursued at SLAC is reviewed. This research includes experiments in laser acceleration, plasma wakefield acceleration, and mmwavelength RF driven accelerators.

  13. Electronic Universal Vote

    Directory of Open Access Journals (Sweden)

    Cristian USCATU

    2008-01-01

    Full Text Available In the days of informational society everything is going online. Most aspects of our lives have online components. Since democracy is a big issue, it could not escape this trend. Governments themselves are moving to the online environment for the purpose of improving their internal efficiency and their availability to the citizens, businesses and other parties interested. Since governments are the result of elections, elections have also been touched by the electronic fever. New electronic voting solutions arise and each one brings new debates with many arguments in their favor and against them. Accessibility and ease of use leads the arguments in favor of electronic voting over the internet, while fear of fraud is the main reason people are avoiding electronics and clinging on classic paper ballots.

  14. ORELA electron guns

    International Nuclear Information System (INIS)

    Christian, O.W.; Lewis, T.A.

    1981-09-01

    The most recent information concerning the production and performance of ORELA electron guns is presented. Included are descriptions of procedures for gun fabrication, cathode conditioning and high voltage processing. Highlights of the performance characteristics are also included

  15. Corrosion in Electronics

    DEFF Research Database (Denmark)

    Ambat, Rajan; Gudla, Helene Virginie Conseil; Verdingovas, Vadimas

    2017-01-01

    Electronic control units, power modules, and consumer electronics are used today in a wide variety of varying climatic conditions. Varying external climatic conditions of temperature and humidity can cause an uncontrolled local climate inside the device enclosure. Uncontrolled humidity together...... and high density packing combined with the use of several materials, which can undergo electrochemical corrosion in the presence of water film formed due to humidity exposure and bias conditions on the PCBA surface. This article provides a short review of the corrosion reliability issues of electronics due...... to the use of electronics under varying humidity conditions. Important PCBA aspects, which are fundamental to the corrosion cell formation under humid conditions, are discussed. Effect of hygroscopic residues from the process and service and their role in assisting water film build up and corrosion...

  16. Paper based electronics platform

    KAUST Repository

    Nassar, Joanna Mohammad; Sevilla, Galo Andres Torres; Hussain, Muhammad Mustafa

    2017-01-01

    A flexible and non-functionalized low cost paper-based electronic system platform fabricated from common paper, such as paper based sensors, and methods of producing paper based sensors, and methods of sensing using the paper based sensors

  17. Electronic personal dosemeters

    International Nuclear Information System (INIS)

    Marshall, T.O.; Bartlett, D.T.; Burgess, P.H.; Cranston, C.S.; Higginbottom, D.J.; Sutton, K.W.

    1990-01-01

    Personal dosimetry services approved by their national authorities for category A workers, invariably use passive dosemeters incorporating photographic film or thermoluminescent detectors. However, the performance characteristics of electronic dosemeters has improved substantially over the past decade to such an extent that in the opening lecture of the Solid State Dosimetry Conference at Oxford in 1986 the development of an electronic 'smart card' based on a silicon detector was briefly discussed. This idea has been taken up and at least one development programme is in progress aimed at the production of an electronic dosemeter suitable for use as a legal device. The more important performance requirements of personal dosemeters for this purpose are discussed and the earlier electronic dosemeter designs and the latest devices under development to meet this specification are compared. (author)

  18. Scanning Auger Electron Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — A JEOL model 7830F field emission source, scanning Auger microscope.Specifications / Capabilities:Ultra-high vacuum (UHV), electron gun range from 0.1 kV to 25 kV,...

  19. Issues in Electronic Publishing.

    Science.gov (United States)

    Meadow, Charles T.

    1997-01-01

    Discusses issues related to electronic publishing. Topics include writing; reading; production, distribution, and commerce; copyright and ownership of intellectual property; archival storage; technical obsolescence; control of content; equality of access; and cultural changes. (Author/LRW)

  20. Modular Lego-Electronics

    KAUST Repository

    Shaikh, Sohail F.; Ghoneim, Mohamed T.; Bahabry, Rabab R.; Khan, Sherjeel M.; Hussain, Muhammad Mustafa

    2017-01-01

    . Here, a generic manufacturable method of converting state-of-the-art complementary metal oxide semiconductor-based ICs into modular Lego-electronics is shown with unique geometry that is physically identifiable to ease manufacturing and enhance

  1. Electron linac injector developments

    International Nuclear Information System (INIS)

    Fraser, J.S.

    1986-01-01

    There is a continuing demand for improved injectors for electron linacs. Free-electron laser (FEL) oscillators require pulse trains of high brightness and, in some applications, high average power at the same time. Wakefield-accelerator and laser-acceleration experiments require isolated bunches of high peak brightness. Experiments with alkali-halide photoemissive and thermionic electron sources in rf cavities for injector applications are described. For isolated pulses, metal photocathodes (illuminated by intense laser pulses) are being employed. Reduced emittance growth in high-peak-current electron injectors may be achieved by linearizing the cavity electric field's radial component and by using high field strengths at the expense of lower shunt impedance. Harmonically excited cavities have been proposed for enlarging the phase acceptance of linac cavities and thereby reducing the energy spread produced in the acceleration process. Operation of injector linacs at a subharmonic of the main linac frequency is also proposed for enlarging the phase acceptance

  2. Electronics for guitarists

    CERN Document Server

    Dailey, Denton J

    2014-01-01

    Electronics for Guitarists focuses on analog circuitry, and is written for the guitarist interested in transistor and vacuum tube-based amplifiers. Topics include discrete transistors and diodes, classical filter circuits, and vacuum tube-based amplifiers.

  3. Nemo-3 calorimeter electronics

    International Nuclear Information System (INIS)

    Bernaudin, P.; Cheikali, C.; Lavigne, B.; Richard, A.; Lebris, J.

    2000-11-01

    The calorimeter electronics of the NEMO-3 double beta decay experiment fulfills three functions: -energy measurement of the electrons by measuring the charge of the pulses, - time measurement, - fast first level triggering. The electronics of the 1940 Scintillator-PM modules is implemented as 40 '9U x 400 mm VME' boards of up to 51 channels. For each channel the analog signals conditioning is implemented as one SMD daughter board. Each board performs 12 bit charge measurements with 0.35 pC charge resolution, 12 bit time measurements with 50 ps time resolution and a fast analog multiplicity level for triggering. The total handling and conversion time for all the channels is less than 100 μs. The electronics will be presented as well as the test system. (authors)

  4. Novel electron gas systems

    International Nuclear Information System (INIS)

    Senatore, G.; Rapisarda, F.; Conti, S.

    1998-01-01

    We review recent progress on the physics of electrons in the bilayered electron gas, relevant to coupled quantum wells in GaAs/AIGaAs heterostructures. First we focus on the phase diagram of a symmetric bilayer at T = B = 0, obtained by diffusion Monte Carlo (DMC) simulations. It is found that inter-layer correlations stabilize crystalline structures at intermediate inter-layer separation, while favoring a liquid phase at smaller distance. Also, the available DMC evidence is in contrast with the recently (Hartree-Fock) predicted total charge transfer (TCT), whereby all the electron spontaneously jump in one layer. In fact, one can show that such a TCT state is never stable in the ideal bilayer with no tunneling. We finally comment on ongoing DMC investigations on the electron-hole bilayer, where excitonic condensation is expected to take place. (Copyright (1998) World Scientific Publishing Co. Pte. Ltd)

  5. Improved electron transport layer

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention provides: a method of preparing a coating ink for forming a zinc oxide electron transport layer, comprising mixing zinc acetate and a wetting agent in water or methanol; a coating ink comprising zinc acetate and a wetting agent in aqueous solution or methanolic solution......; a method of preparing a zinc oxide electron transporting layer, which method comprises: i) coating a substrate with the coating ink of the present invention to form a film; ii) drying the film; and iii) heating the dry film to convert the zinc acetate substantially to ZnO; a method of preparing an organic...... photovoltaic device or an organic LED having a zinc oxide electron transport layer, the method comprising, in this order: a) providing a substrate bearing a first electrode layer; b) forming an electron transport layer according to the following method: i) coating a coating ink comprising an ink according...

  6. Magnetic electron scattering

    International Nuclear Information System (INIS)

    Peterson, G.A.

    1989-01-01

    We briefly review some of the motivations, early results, and techniques of magnetic elastic and inelastic electron-nucleus scattering. We then discuss recent results, especially those acquired at high momentum transfers. 50 refs., 19 figs

  7. Advances in electron dosimetry

    International Nuclear Information System (INIS)

    Harder, D.

    1980-04-01

    Starting from the two most important interactions of electrons with matter, energy loss and scattering, a review is given of a number of effects which are important in electron dosimetry. For determining the absorbed dose in a phantom by means of ionization chambers, imformation is required on the electron spectrum at the location of the measurement, on the stopping powers of different materials and on disturbances such as the displacement of the effective point of measurements from the centre of the chamber. By means of figures and photographs of electron traces in bubble chambers, the origin of the formation of the absorbed dose maximum in a phantom is explained. It is shown, how by multiple scattering, the similarity of dose distributions in different media can be explained and how by Monte-Carlo calculations absorbed dose distributions in the surroundings of inhomogeneities (e.g. cavities) in a phantom can be determined. (orig.) [de

  8. Electron gun for SSRF

    International Nuclear Information System (INIS)

    Sheng Shugang; Lin Guoqiang; Gu Qiang; Li Deming

    2003-01-01

    A 100 kV triode-electron-gun has been designed and manufactured for the Linac of Shanghai Synchrotron Radiation Facility (SSRF). In this paper the performance of the gun and some key components are described

  9. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  10. ELECTRONIC BANKING AND ELECTRONIC COMMERCE IN SERBIA

    Directory of Open Access Journals (Sweden)

    Ivana B. Petrevska

    2014-10-01

    Full Text Available Nowadays, we may witness to dramatic and visible changes in our life environment. Business ambient for companies is different every day, and it is very hard to predict a direction of future changes. There is an environment characterized by sharp competition and increasing number of competitors, fast technological improvements and highly sophisticated and informed costumers. Technological process influences the humanity strongly, changing the way that people live, work and spend. Electronic commerce and electronic banking has become incontinent, and makes a great part of today's total transactions. There are an increasing number of companies that perform their business that way and make profit. Social networks are proven to be the least expensive way of information exchange, and they are present in almost every part of the world. The globalization has reached the most distant parts of the Earth. Every resistance to new technologies is dangerous and may lead to bankruptcy. Due to the EU expansion, Internet users are to be expected, and prosperity of the e-commerce business models at the same time. In Serbia, electronic commerce is present, but not as developed as in EU countries. E-commerce, however it might be successful throughout the world, it is somewhat slow in its growth in Serbia. The reasons are numerous, and main obstacles are the lack of trust, still limited usage of banking cards, avoiding of e-payments by older population etc. Also, the recent scandals over the misuse of personal data, and e-crime are discouraging factors for the growth of e-trade and ebanking. The younger generations are ever more ready to use e-commerce, since they are open to new technologies and do not have the defensive attitude towards it. E-commerce and e-banking has growing potential even among older population, if the society prevents them from fear and mistrust.

  11. Thermionics basic principles of electronics

    CERN Document Server

    Jenkins, J; Ashhurst, W

    2013-01-01

    Basic Principles of Electronics, Volume I : Thermionics serves as a textbook for students in physics. It focuses on thermionic devices. The book covers topics on electron dynamics, electron emission, and the themionic vacuum diode and triode. Power amplifiers, oscillators, and electronic measuring equipment are studied as well. The text will be of great use to physics and electronics students, and inventors.

  12. Low emittance thermionic electron guns

    International Nuclear Information System (INIS)

    Herrmannsfeldt, W.B.

    1989-01-01

    The author discusses self-field effects and external field effects for electron guns. He also discusses designs of electron guns and their uses in electron cooling systems and as an injector for electrostatic free electron lasers. He closes by looking at electron guns for linear accelerators. 20 references, 3 figures

  13. A new stage of nuclear electronics-particle electronics

    International Nuclear Information System (INIS)

    Xi Deming

    1987-01-01

    The rapid development of high energy physics experiments has pushed the nuclear electronics to a new stage, i.e. the particle electronics. In this paper the background, main features and recent trends of the particle electronics are expounded

  14. Electron attachment cross sections obtained from electron attachment spectroscopy

    International Nuclear Information System (INIS)

    Popp, P.; Baumbach, J.I.; Leonhardt, J.W.; Mothes, S.

    1988-01-01

    Electron capture detectors have a high sensitivity for substances with high thermal electron attachment cross sections. The electron attachment spectroscopy makes it possible to change the mean electron energy in such a way that the maximum for dissociative electron attachment is reached. Thus, best operation modes of the detection system as well as significant dependencies of electron attachment coefficients are available. Cross sections for electron attachment as a function of the electron energy are obtained with the knowledge of electron energy distribution functions from Boltzmann equation analysis by a special computer code. A disadvantage of this electron attachment spectroscopy is the superposition of space charge effects due to the decrease of the electron drift velocity with increasing mean electron energy. These influences are discussed. (author)

  15. Auroal electron distribution function

    International Nuclear Information System (INIS)

    Kaufmann, R.L.; Dusenbery, P.B.; Thomas, B.J.; Arnoldy, R.L.

    1978-01-01

    The electron velocity distribution function is presented in the energy range 25 eV 8 cm/s (E=300 eV) are nearly isotropic in pitch angle throughout the flight. Upgoing electrons show almost no pitch angle dependence beyond 120 0 , and their fluxes decline smoothly as energy increases, with little or no evidence of a plateau. Preliminary results of numerical integrations, to study bulk properties and stability of the plasma are presented

  16. Mathematics for electronic technology

    CERN Document Server

    Howson, D P

    1975-01-01

    Mathematics for Electronic Technology is a nine-chapter book that begins with the elucidation of the introductory concepts related to use of mathematics in electronic engineering, including differentiation, integration, partial differentiation, infinite series, vectors, vector algebra, and surface, volume and line integrals. Subsequent chapters explore the determinants, differential equations, matrix analysis, complex variable, topography, graph theory, and numerical analysis used in this field. The use of Fourier method for harmonic analysis and the Laplace transform is also described. The ma

  17. Electricity electron measurement

    International Nuclear Information System (INIS)

    Kim, Sang Jin; Sung, Rak Jin

    1985-11-01

    This book deals with measurement of electricity and electron. It is divided into fourteen chapters, which depicts basic of electricity measurement, unit and standard, important electron circuit for measurement, instrument of electricity, impedance measurement, power and power amount measurement, frequency and time measurement, waveform measurement, record instrument and direct viewing instrument, super high frequency measurement, digital measurement on analog-digital convert, magnetic measurement on classification by principle of measurement, measurement of electricity application with principle sensors and systematization of measurement.

  18. Electron affinities: theoretical

    International Nuclear Information System (INIS)

    Kaufman, J.J.

    1976-01-01

    A brief description is given of the conceptual background and formalism of the various ab-initio and semi-ab-initio quantum computational techniques for calculating atomic and molecular electron affinities: Hartree--Fock--Roothaan SCF, configuration interaction (CI), multiconfiguration SCF (MC-SCF), Bethe--Goldstone, superposition of configurations (SOC), ab-initio effective core model potentials, Xα-MS, plus other less common methods. Illustrative and comparative examples of electron affinities calculated by these various methods are presented

  19. Electronics practice technology

    International Nuclear Information System (INIS)

    1995-01-01

    This book concentrates on electronic technology. It deals with kinds of terminal and mounting such as teflon terminal, steatite terminal, and harmonica terminal, small parts like connector, plug jack, vernier dial, and coupling, termination of wiring, kinds of switch and mounting, a condenser, fixed resistor, trance coil, loading of semiconductor, mounting of high input impedance circuit, mounting of electric power circuit, manufacturing of print substrate and practice of manufacturing for print substrate. This is one of series books on electronic technology.

  20. Electron-ion collisions

    International Nuclear Information System (INIS)

    Crandall, D.H.

    1982-01-01

    This discussion concentrates on basic physics aspects of inelastic processes of excitation, ionization, and recombination that occur during electron-ion collisions. Except for cases of illustration along isoelectronic sequences, only multicharged (at least +2) ions will be specifically discussed with some emphasis of unique physics aspects associated with ionic charge. The material presented will be discussed from a primarily experimental viewpoint with most attention to electron-ion interacting beams experiments

  1. Newnes electronics toolkit

    CERN Document Server

    Phillips, Geoff

    2013-01-01

    Newnes Electronics Toolkit brings together fundamental facts, concepts, and applications of electronic components and circuits, and presents them in a clear, concise, and unambiguous format, to provide a reference book for engineers. The book contains 10 chapters that discuss the following concepts: resistors, capacitors, inductors, semiconductors, circuit concepts, electromagnetic compatibility, sound, light, heat, and connections. The engineer's job does not end when the circuit diagram is completed; the design for the manufacturing process is just as important if volume production is to be

  2. Electronic states of myricetin

    DEFF Research Database (Denmark)

    Vojta, Danijela; Karlsen, Eva; Spanget-Larsen, Jens

    2017-01-01

    Myricetin (3,3',4',5,5',7'-hexahydroxyflavone) was investigated by linear dichroism spectroscopy on molecular samples partially aligned in stretched poly(vinyl alcohol) (PVA). At least five electronic transitions in the range 40000 – 20000 cm–1 were characterized with respect to their wavenumbers......, relative intensities, and transition moment directions. The observed bands were assigned to electronic transitions predicted with TD-B3LYP/6-31+G(d,p)....

  3. Newnes electronics assembly handbook

    CERN Document Server

    Brindley, Keith

    2013-01-01

    Newnes Electronics Assembly Handbook: Techniques, Standards and Quality Assurance focuses on the aspects of electronic assembling. The handbook first looks at the printed circuit board (PCB). Base materials, basic mechanical properties, cleaning of assemblies, design, and PCB manufacturing processes are then explained. The text also discusses surface mounted assemblies and packaging of electromechanical assemblies, as well as the soldering process. Requirements for the soldering process; solderability and protective coatings; cleaning of PCBs; and mass solder/component reflow soldering are des

  4. The Recycler Electron Cooler

    Energy Technology Data Exchange (ETDEWEB)

    Shemyakin, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Prost, L. R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2013-03-19

    The Recycler Electron cooler was the first (and so far, the only) cooler working at a relativistic energy (γ = 9.5). It was successfully developed in 1995-2004 and was in operation at Fermilab in 2005-2011, providing cooling of antiprotons in the Recycler ring. This paper describes the cooler, difficulties in achieving the required electron beam parameters and the ways to overcome them, cooling measurements, and details of operation.

  5. Weakly oval electron lense

    International Nuclear Information System (INIS)

    Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.

    2001-01-01

    The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system

  6. Electronics 3 checkbook

    CERN Document Server

    Knight, S A; May, A J C

    2013-01-01

    Electronics 3 Checkbook provides a concise coverage of the theories and definitions of concepts in electronics. The book provides problems and worked examples to supplement fuller textbooks of the same subject. The coverage of the text includes decibel measurement, operational amplifiers, DA and AD converters, controlled rectifiers, triggering devices, optoelectronic devices, fiber optics, and power amplifiers. The text will be of great use to electrical engineering students who wish to enhance their understanding of the basics of mechanical and electrical science.

  7. Antifragile Electronic Warfare

    OpenAIRE

    Lichtman, Marc

    2014-01-01

    This letter introduces the concept of antifragile electronic warfare (EW), which we define as the ability to allow a communications link to improve performance due to the presence of a jammer. This concept should not be confused with jamming countermeasures (a.k.a. anti-jamming or electronic protection). Rather, antifragile EW can be thought of as the next step beyond simply avoiding or mitigating jamming. After introducing the concept we narrow down the subset of jammers this concept can be ...

  8. Electrical and electronic principles

    CERN Document Server

    Knight, SA

    1988-01-01

    Electrical and Electronic Principles, 3 focuses on the principles involved in electrical and electronic circuits, including impedance, inductance, capacitance, and resistance.The book first deals with circuit elements and theorems, D.C. transients, and the series circuits of alternating current. Discussions focus on inductance and resistance in series, resistance and capacitance in series, power factor, impedance, circuit magnification, equation of charge, discharge of a capacitor, transfer of power, and decibels and attenuation. The manuscript then examines the parallel circuits of alternatin

  9. Nuclear electronics laboratory manual

    International Nuclear Information System (INIS)

    1984-05-01

    The Nuclear Electronics Laboratory Manual is a joint product of several electronics experts who have been associated with IAEA activity in this field for many years. The manual does not include experiments of a basic nature, such as characteristics of different active electronics components. It starts by introducing small electronics blocks, employing one or more active components. The most demanding exercises instruct a student in the design and construction of complete circuits, as used in commercial nuclear instruments. It is expected that a student who completes all the experiments in the manual should be in a position to design nuclear electronics units and also to understand the functions of advanced commercial instruments which need to be repaired or maintained. The future tasks of nuclear electronics engineers will be increasingly oriented towards designing and building the interfaces between a nuclear experiment and a computer. The manual pays tribute to this development by introducing a number of experiments which illustrate the principles and the technology of interfacing

  10. Auroral electron energies

    International Nuclear Information System (INIS)

    McEwan, D.J.; Duncan, C.N.; Montalbetti, R.

    1981-01-01

    Auroral electron characteristic energies determined from ground-based photometer measurements of the ratio of 5577 A OI and 4278 A N 2 + emissions are compared with electron energies measured during two rocket flights into pulsating aurora. Electron spectra with Maxwellian energy distributions were observed in both flights with an increase in characteristic energy during each pulsation. During the first flight on February 15, 1980 values of E 0 ranging from 1.4 keV at pulsation minima to 1.8 keV at pulsation maxima were inferred from the 5577/4278 ratios, in good agreement with rocket measurements. During the second flight on February 23, direct electron energy measurements yielded E 0 values of 1.8 keV rising to 2.1 keV at pulsation maxima. The photometric ratio measurements in this case gave inferred E 0 values about 0.5 keV lower. This apparent discrepancy is considered due to cloud cover which impaired the absolute emission intensity measurements. It is concluded that the 5577/4278 ratio does yield a meaningful measure of the characteristic energy of incoming electrons. This ratio technique, when added to the more sensitive 6300/4278 ratio technique usable in stable auroras can now provide more complete monitoring of electron influx characteristics. (auth)

  11. Netiquette in Electronic Communication

    Directory of Open Access Journals (Sweden)

    Tomáš Kozík

    2014-06-01

    Full Text Available Electronic mail and electronic communications systems are considered significant and effective tools of communication. One of the most widespread electronic communication tools is e - mail communication. In order to avoid misinterpretation of the report on the side of the recipient, it is need to pay attention to the writing of e - mail messages as well as to their content. With the continuous expansion of the use of electronic communication there have gradually developed certain rules of etiquette in electronic communications. The existing rules of the propriety ones are expressed in the term " etiqutte " and are not automatically applied in the new communications environment - media. For electronic communication, the new rules of etiquette have been stabilised into a term NETIQUETTE. The word netiquette was created by combining words NET (net and ETIKETA (a set of rules of social behavior and habits. Netiquette constitutes the rules of the behavior of users on a network. Although the netiquette is merely "an unwritten set of rules", their not using can be understood as a type of disrespect. Analysis of knowledge of domestic and foreign sources as well as results of a survey confirmed the justification of paying attention to the education of individuals in NETIQUETTE, irrespective of the degree of education.

  12. HDTV versus electronic cinema

    Science.gov (United States)

    Tinker, Michael

    1998-12-01

    We are on the brink of transforming the movie theatre with electronic cinema. Technologies are converging to make true electronic cinema, with a 'film look,' possible for the first time. In order to realize the possibilities, we must leverage current technologies in video compression, electronic projection, digital storage, and digital networks. All these technologies have only recently improved sufficiently to make their use in the electronic cinema worthwhile. Video compression, such as MPEG-2, is designed to overcome the limitations of video, primarily limited bandwidth. As a result, although HDTV offers a serious challenge to film-based cinema, it falls short in a number of areas, such as color depth. Freed from the constraints of video transmission, and using the recently improved technologies available, electronic cinema can move beyond video; Although movies will have to be compressed for some time, what is needed is a concept of 'cinema compression,' rather than video compression. Electronic cinema will open up vast new possibilities for viewing experiences at the theater, while at the same time offering up the potential for new economies in the movie industry.

  13. Transformational III-V Electronics

    KAUST Repository

    Nour, Maha A.

    2014-01-01

    Flexible electronics using III-V materials for nano-electronics with high electron mobility and optoelectronics with direct band gap are attractive for many applications. This thesis describes a complementary metal oxide semiconductor (CMOS

  14. Beginning analog electronics through projects

    CERN Document Server

    Singmin, Andrew

    2001-01-01

    Analog electronics is the simplest way to start a fun, informative, learning program. Beginning Analog Electronics Through Projects, Second Edition was written with the needs of beginning hobbyists and students in mind. This revision of Andrew Singmin's popular Beginning Electronics Through Projects provides practical exercises, building techniques, and ideas for useful electronics projects. Additionally, it features new material on analog and digital electronics, and new projects for troubleshooting test equipment.Published in the tradition of Beginning Electronics Through Projects an

  15. Electron Accumulative Molecules.

    Science.gov (United States)

    Buades, Ana B; Sanchez Arderiu, Víctor; Olid-Britos, David; Viñas, Clara; Sillanpää, Reijo; Haukka, Matti; Fontrodona, Xavier; Paradinas, Markos; Ocal, Carmen; Teixidor, Francesc

    2018-02-28

    With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B-N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B-N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C 2 B 9 H 11 )(C 2 B 9 H 10 )-NC 5 H 4 -C 5 H 4 N-M'(C 2 B 9 H 11 )(C 2 B 9 H 10 )] (M = M' = Co, Fe and M = Co and M' = Fe) and semi(metallacarboranyl)viologen [3,3'-M(8-(NC 5 H 4 -C 5 H 4 N-1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )] (M = Co, Fe) electron cumulative molecules. These molecules are able to accept up to five electrons and to donate one in single electron steps at accessible potentials and in a reversible way. By targeted synthesis and corresponding electrochemical tests each electron transfer (ET) step has been assigned to specific fragments of the molecules. The molecules have been carefully characterized, and the electronic communication between both metal centers (when this situation applies) has been definitely observed through the coplanarity of both pyridine fragments. The structural characteristics of these molecules imply a low reorganization energy that is a necessary requirement for low energy ET processes. This makes them electronically comparable to fullerenes, but on their side, they have a wide range of possible solvents. The ET from one molecule to another has been clearly demonstrated as well as their self-organizing capacity. We consider that these molecules, thanks to their easy synthesis, ET, self-organizing capacity, wide range of solubility, and easy processability, can

  16. Electronic Submissions of Pesticide Applications

    Science.gov (United States)

    Applications for pesticide registration can be submitted electronically, including forms, studies, and draft product labeling. Applicants need not submit multiple electronic copies of any pieces of their applications.

  17. Electron beams and applications

    International Nuclear Information System (INIS)

    Haouat, G.; Couillaud, C.

    1998-01-01

    Studies of the physical properties of the ELSA-linac electron beam are presented. They include measurements of the characteristic beam parameter and analyzes of the beam transport using simulation codes. The aim of these studies is to determine the best conditions for production of intense and very short electron bunches and to optimize the transport of space-charge dominated beams. Precise knowledge of the transport dynamics allows to produce beams with the required characteristics for light production in Free-Electron Laser (FEL), and to give a good description of energy-transfer phenomena between electrons and photons in the wriggler. The particular features of ELSA authorize studies of high-intensity, high-brightness beam properties, especially the halo surrounding the dense core of the electron bunches, which is formed by the space charge effects. It is also shown that the ELSA facility is well suited for the fabrication of very short γ and X-rays sources for applied research in nuclear and plasma physics, or for time response studies of fast detectors. (author)

  18. Auroral electron time dispersion

    International Nuclear Information System (INIS)

    Kletzing, C.A.

    1989-01-01

    A sounding rocket flight was launched from Greenland in 1985 to study high latitude, early morning auroral physics. The payload was instrumented with electron and ion detectors, AC and DC electric field experiments, a plasma density experiment, and a magnetometer to measure the ambient field. The rocket was launched during disturbed conditions, when the polar cap was in a contracted state with visible aurora overhead. The electron data contained numerous signatures indicative of time-of-flight energy dispersion characterized by a coherent structure in which lower energy electrons arrived at the rocket after higher energy electrons. A model was constructed to explain this phenomena by the sudden application of a region of parallel electric field along a length of magnetic field line above the rocket. The model incorporates detector response and uses an altitudinal density profile based on auroral zone measurements. Three types of potential structures were tried: linear, quadratic and cubic. Of the three it was found that the cubic (electric field growing in a quadratic manner moving up the field line) produced the best fit to the data. The potential region was found to be approximately 1-2 R e in extent with the lower edge 3000-4000 km away from the rocket. The background electron temperature in the model which produced the best fit to the data was of the order of 15 eV

  19. Electron irradiation of zeolites

    International Nuclear Information System (INIS)

    Wang, S.X.; Wang, L.M.; Ewing, R.C.

    1999-01-01

    Three different zeolites (analcime, natrolite, and zeolite-Y) were irradiated with 200 keV and 400 keV electrons. All zeolites amorphized under a relatively low electron fluence. The transformation from the crystalline-to-amorphous state was continuous and homogeneous. The electron fluences for amorphization of the three zeolites at room temperature were: 7.0 x 10 19 e - /cm 2 (analcime), 1.8 x 10 20 e - /cm 2 (natrolite), and 3.4 x 10 20 e - /cm 2 (zeolite-Y). The different susceptibilities to amorphization are attributed to the different channel sizes in the structures which are the pathways for the release of water molecules and Na + . Natrolite formed bubbles under electron irradiation, even before complete amorphization. Analcime formed bubbles after amorphization. Zeolite-Y did not form bubbles under irradiation. The differences in bubble formation are attributed to the different channel sizes of the three zeolites. The amorphization dose was also measured at different temperatures. An inverse temperature dependence of amorphization dose was observed for all three zeolites: electron dose for amorphization decreased with increasing temperature. This unique temperature effect is attributed to the fact that zeolites are thermally unstable. A semi-empirical model was derived to describe the temperature effect of amorphization in these zeolites

  20. Politics Under Electronic Simultaneity

    Directory of Open Access Journals (Sweden)

    Valery P. Terin

    2014-01-01

    Full Text Available In contradistinction to the book and the other typographic products, the electronic media operates on a 24-hour-a-day basis evoking simultaneity as the guiding mode of perception and thinking for all those under its influence. The discovery of this fact manifested itself in the formation and development of the managerial technologies operating by means of the electronic information environment and following the principle of simultaneity in the first place. Thus, at the end of the 1960s already the election campaigns in the U.S.A. began to operate on the basis of the final cause as the guiding principle of the country's mass consciousness motivating to carry out each particular event as if already rejoicing at the victory. With this in mind, there emerged a problem of applying this approach with its enormous managerial potential elsewhere. To add, simultaneity as a norm of perception and thinking turned out to be increasingly important with the advent of the electrical telegraph and the press relying on its short disconnected messages instantaneously arriving from all parts of the world. All the other media, which emerged in the wake of this development, has served to fortify this mode of thought as governing in the electronic information environment. The potential of the electronically operating global managerial technologies is quickly growing. The article also deals with the information overload and pattern recognition problem understood in managerial terms as well as mythologization and demythologization processes as they are necessitated by the electronic media coverage worldwide.