472 research outputs found
Dynamic and thermodynamic crossover scenarios in the Kob-Andersen mixture: Insights from multi-CPU and multi-GPU simulations
No full text<p>This dataset is associated with "Dynamic and thermodynamic crossover scenarios in the Kob-Andersen mixture: Insights from multi-CPU and multi-GPU simulations", Daniele Coslovich, Misaki Ozawa, and Walter Kob, Eur. Phys. J. E 62, 41 (2018) [<a href="https://doi.org/10.1140/epje/i2018-11671-2">doi:10.1140/epje/i2018-11671-2</a> <a href="https://arxiv.org/abs/1804.04559">arXiv:1804.04559</a>]</p>
<p>It includes scripts and data files to allow for the replication of the figures. EPS figures were generated using gnuplot version 5.0.</p>
<p>Notes:</p>
<ul>
<li>Small differences in the dynamic data for the N=3600 dataset obtained with the MD protocol reflect additional statistics gathered since acceptance of the paper.</li>
<li>Figure 6(b) in the published version of the manuscript was obtained using slightly incorrect values of the parameters J, T_0 entering equation 10. This minor issue has been fixed in this dataset.</li>
</ul>
Enrichment of rotifers (Branchionus plicatilis), Artemia nauplii and artificial dry feed with live yeast (Debaryomyces hansenii) for the growth of cultured dusky kob (Argyrosomus japonicus) larvae
No full textAquaculture has expanded dramatically over the last fifty years and now contributes almost half of the global total fish production. Since fish are a very important source of protein for humans, aquaculture is an important food source and economic practice. It is therefore important to minimise and manage any factors that may negatively impact on aquaculture operations. One of the major problems in marine fish aquaculture is the high rate of larval mortality in captivity. One way of combatting this problem is by improving overall health of larvae. Probiotics, especially yeasts, can be used as immune boosters, disease control agents and a source of additional nutrients to help minimise this problem. These probiotics can be effectively administered to larvae using live feeds, such as rotifers and Artemia, and formulated feeds. The dusky kob, Argryosomus japonicus, is emerging as a commercially viable marine aquaculture species in South Africa. However, commercial production of this species is being hindered by parasitic disease. Therefore, this study tested the efficacy of (1) incorporating live culturable Debaryomyces hansenii (yeast) cells into rotifers (Branchionus plicatilis), Artemia nauplii and a formulated feed (Nutroscience Pre-starter Crumble), and (2) investigated the effects of the probiotic supplemented feeds on growth and survival of dusky kob larvae. We demonstrated that live culturable yeast cells, incubated at a period of 0.5 hours, delivered significantly more yeast cells per rotifer than the longer incubation periods (p<0.001). For Artemia, the incubation period of 0.5 hours delivered more yeast cells per Artemia, but this incubation period was not significantly better than the longer incubation periods (p=0.204). The starting yeast concentration of 1 x 1012 yeast cells.ml-1 resulted in significantly more yeast cells per rotifer (p=0.042) and Artemia (p<0.001) than the lower starting yeast concentrations. The proliferation of Debaryomyces hansenii on the formulated (dry) feed is significantly higher at a storage temperature of 4 °C than it is at a storage temperature of 20 °C (p<0.001). This could however, be causing a deterioration in the stability of the feed. The number of yeast cells per g of feed significantly decreases after 14 days, indicating a possible loss of culturability and stability of the yeast in the feed, regardless of the storage temperature (p<0.001 for 4 °C; p<0.05 for 20 °C). Drying the feed after coating it in yeast also causes a significant reduction in the number of yeast cells per g of feed (p<0.001). With more replication and more cautionary experimental design, this experiment could be repeated in the future. Unfortunately, the mortality rate of the larvae was so high that the results obtained for the larval growth trials could not be statistically analysed, even though rotifer and Artemia (live feed) incubations were performed
Derivation of Spatial Information from a Multi-Channel Electroglottograph
No full textComplex laryngeal manoeuvres occur during swallowing and singing register changes. These actions require an accurate synchronization of vocal fold adduction/abduction and the change of the larynx position. In case of dysfunction, this synchronization can be disturbed. The simultaneous assessment of glottal dynamics (typical EGG signal) and larynx position can be beneficial for the diagnosis of disordered voice and swallowing. Up to now, there isn’t the possibility to derive instantly these two information because of technology problems. We used a time-multiplex measurement approach of space-resolved transfer impedances through the larynx (MC-EGG). We developed a software Labview code for the visualization of the main waveforms in the study of the EGG signals. Moreover the data acquired by Labview have been used to create a theoretical algorithm for deriving the position of the larynx inside the neck. We verified the results of the algorithm for the 3D larynx movement comparing the data acquired with the values described in literature. The paths of the larynx and the displacement on the vertical and sagittal plans match the known ones for the emission of low/high notes and for the swallowing. Besides we have introduced the possibility to study the movement on the coronal plan (unexplored up to now) that can be a starting point for new analysis
Derivazione di infomazioni spaziali tramite un elettroglottografo multi-canale
No full textIl lavoro è focalizzato in particolare sul tema della valutazione in real-time dell’oscillazione delle corde vocali e del movimento della laringe all’interno della gola durante alcuni atti fonatori. Lo sviluppo del lavoro ha visto una parte di adattamento hardware del prototipo di Elettroglottografo Multi-Canale (MC-EGG) e l’implementazione di un algoritmo per il calcolo e la visualizzazione del movimento spaziale della laringe a partire da misure di transimpedenza acquisite da due matrici di elettrodi (2x3) rapidamente switchati nel tempo
Kobus kob
No full text126. Buffon’s Kob Kobus kob French: Cobe de Buffon / German: Senegal-Grasantilope / Spanish: Kob de Buffon Other common names: Senegal Kob, Western Kob Taxonomy. Antilope kob Erxleben, 1777, Upper Guinea. Buffon’s Kob formerly encompassed all kob species from western, central, and eastern Africa. Based on skull characteristics, the four former subspecies have been elevated to species, and K. kob is now taken to be restricted to Africa west of Nigeria. This species is considered monotypic here. Distribution. Senegal to W Nigeria. Descriptive notes. Head-body ¢.160-180 cm, tail 10-15 cm, shoulder height 90-100 cm (males) and 82-92 cm (females); weight 60 kg (males) and 45 kg (females). Buffon’s Kob is a relatively small kob. The pelage is short and smooth. The overall color is golden brown or orange, and the underparts and inner surfaces of the legs are white. The outer surfaces of the legs are the same color as the body. An indistinct black stripe is present on the front of all four limbs, and a white band is present above the hooves. On the face, white markings are present around the eyes, at the base of each ear, and on the muzzle and lips. The ears have pale interiors and golden backs with blackish tips. The lyre-shape horns are present only in males; as with body size, the horns of Buffon’s Kob tend to be smaller than those of other kobs. Average length in mature males is 48-55 cm;their spread at the tips may be 14-37 cm depending on the degree of divergence at the base and the inward curvature at the tips. Dental formula i510/3,C0/1,P3/3,M 3/3 (x2) =32 Habitat. Savannas and alluvial plains. Buffon’s Kob inhabits grasslands closely associated with lakes and rivers; it is rarely found more than a few kilometers away from a permanent water source, particularly during the dry season. Open savannas are the principal habitat during the wet season (approximately 70% of sightings occur in this zone). In the dry season, grass savannas with trees (especially Combretum, Terminalia macroptera, and Detarium) and bushes are preferred (at a similar rate of 70% of sightings). Dense gallery forests are avoided. Historically, population densities of Buffon’s Kob were highest in savannas, averaging 9-20 ind/km?; the onset of the rainy season (April) produced extremely high local densities of up to 97 ind/km?. However,as a result of habitat destruction and hunting, current population densities across the range of Buffon’s Kob are generally less than 1 ind/km?, in some cases below 0-1 ind/km?. Food and Feeding. A selective grazer. Buffon’s Kob feeds on grass throughoutthe year, but tends to be less selective during the wet season. Dry season burns coupled with the rains create a flush of new growth at the start of the wet season; grasses like Andropogon africanus, A. gayanus, A. tectorum, Echinochloa colonum, and Brachiaria mutica are favored at this time of year. In the wooded savannas used during the dry season, Hyparrhenia subplumosa, Schizachyrium sanguineum, and Vetiveria fulvibarbis are preferentially consumed; Buffon’s Kob will also occasionally browse on the young leaves of woody plants (e.g. Digitaria ciliaris). This species drinks daily, and may consume mineral-rich soils, particularly during the dry season when the mineral content of grasses is lowest. Breeding. Buffon’s Kob may breed throughout the year, although a peak in matings is seen in February and March. Births are usually concentrated at the start of the dry season (December—January in Ivory Coast). The breeding system appears to be density-dependent. Lekking, as seen in the Uganda Kob (K. thomasi) and the White-eared Kob (K. leucotis), formerly occurred in areas where population density exceeded approximately 15 ind/km?; these densities are rare in modern West Africa, and lekking is now uncommon. Breeding males tend to be territorial; females pass freely through territories without any attempt on behalf of the male to prevent their egress. A male will follow an estrous female with his neck stretched forward and head low. Ritualized foreleg kicks (“laufschlag”) are a prelude to mounting. Other reproductive parameters are unknown but are likely similar to those of the Uganda Kob. Interbirth intervals tend to be longer than twelve months. Juvenile males are generally forced from their natal herds at eight months of age. Life expectancy in the wild is estimated to be 6-7 years. Activity patterns. Buffon’s Kob tends to be active throughout the day and night. Diurnal observations of captive animals indicate a peak in foraging from 09:00 h to 11:00 h and from 17:00 h to nightfall. Unusually, these animals were observed to rest and ruminate in the early morning, a time when activity levels among ungulates are often high; whether the animals were using the early hours to warm up after night-time foraging or were expressing an artifact of their captivity is unknown. A more typical period of rest and rumination occurs at midday, from 12:00 h to 15:00 h. Of the daylight activity budget, 43-3% is spent feeding; a similar proportion (38:3%) is spent ruminating. Activity levels, as measured by distances traveled, are higher during the day (average displacement of 2-4 km) than at night (1-9 km). Distances covered tend to be greater during the dry season (December—March) in response to less abundant food resources. Movements, Home range and Social organization. Buffon’s Kob displays a variety of social patterns, from solitary individuals to large herds of 100 animals or more. A documented decline in population numbers has been accompanied by a shift in social organization toward smaller herds and largerterritories. The largest groups are observed during the dry season (December-March), when Buffon’s Kobs travel en masse to drinking sites. These large herds are usually temporary, fragmenting after returning to wooded savanna where most dry season foraging occurs. Large herds also form at the beginning of rainy season (April-July) when the species emerges onto open grasslands. In 1974, the typical group size across the year was estimated to be 20 animals; however, herds of 1-5 animals now account for over 70% of observed groupings. Buffon’s Kob herds are very flexible: individuals often join or leave, so the composition of any given group is usually different after a five-hour period. Females constitute the majority of individuals in large herds. Males are more solitary, although young males associate in bachelor herds (these male-only herds are largest during the wet season). Solitary Buffon’s Kobs account for a significant proportion of observations. Isolated males are often territorial and exclude other males from their home ranges even when no females are present. Average territory size is between 0-63 km*and 0-92 km* (range 0-36-1-27 km?); this is significantly smaller than the average home range of females (2: 46 km?). In the 1970s, reported territory size was much smaller (0-03-0-13 km?): the disparity is thought to be due to continued declines in population densities. In Ivory Coast, males show territorial tendencies beginning at three years of age, and most (c.90%) adult males maintain a territory. Territorial boundaries are maintained using displays, including a “proud gait” in which the head is held high and erect. Fights are generally rare. As in the related reedbucks (Redunca spp.), distinctive whistles may indicate to other males that a territory is occupied. Males occupy their territories throughout the year and, although they may leave to drink during droughts, the boundaries themselves are not affected by season. Females frequently shift their home rangesin the late wet season (August-November) to take advantage of changing food resources. Status and Conservation. Classified as Vulnerable on The IUCN Red List (under K. kob kob; this classification also includes western populations of K. loderi). Buffon’s Kob is severely threatened by habitat loss due to agriculture and excessive hunting by humans; it has been extirpated from large parts of its former range. The majority of surviving Buffon’s Kobs are restricted to protected areas, and even these populations have declined (some by over 90%) in recent decades. The total population is likely 40,000 — 75,000, with a large proportion (¢.26,000) inhabiting Niokolo-Koba National Park in Senegal. Other significant populations are found in Arli National Park (Burkina Faso), Comoé National Park (Ivory Coast), and Mole and Bui National Parks (Ghana). Bibliography. Agbelusi (1989, 1991), East (1999), Fischer & Linsenmair (1999, 2001b, 2002, 2007), Geerling & Bokdam (1971), IUCN/SSC Antelope Specialist Group (2008y), Kingdon (1997), Lydekker (1914), Muhlenberg & Roth (1985), Sodeinde (1989).Published as part of Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, pp. 444-779 in Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona :Lynx Edicions on pages 630-631, DOI: 10.5281/zenodo.651248
Resource limitation and population ecology of white-eared kob
No full textIn this study I examine the effect of seasonal resource limitation on the behaviour and population dynamics of white-eared kob, Kobus kob leucotis, in the Boma region of the southern Sudan. This population, numbering over 800,000, migrates seasonally between savannah grasslands in areas with low rainfall and ephemerally swamped grasslands in areas with high rainfall. The aims of the study were: (1) to examine whether kob migration tracks ephemeral distributions of food or water resources, (2) to test the hypothesis that the Boma kob population is limited by food availability, (3) to determine if calf production is cued to seasonal peaks in food abundance, and (4) to evaluate the effect of breeding synchrony on lekking behavior and male competition.
Seasonal climatic changes produced pronounced changes in the distribution and abundance of both green forage and water supplies. Dry season migration primarily tracked limited supplies of water. Within the dry season range, kob aggregated at high densities (over 1,000 per km²) in low-lying meadows that supported grass re-growth when little green grass was available elsewhere in the ecosystem. However, southerly movements in the wet season were not explainable by the resource hypothesis, since both food and water were widely distributed during the wet season. I suggest that kob may move southward in order to avoid surface flooding during the wet season.
Kob mortality during the dry seasons of 1982 and 1983 was considerably higher than estimated mortality during the wet season. Unusual rainfall during the dry season of 1982 provided a "natural experiment" to test the food limitation hypothesis. Adult mortality was significantly lower during the dry season of 1982 than during the more typical dry season of 1983. Calf mortality did not vary significantly between years. Adult mortality rates were related to dry season duration. Dry season mortality was related to sub-maintenance food intake and declining fat reserves. The age structure of the kob population in 1983 suggests that large-scale mortality (ca. 40%) occurred in the 1980 drought that immediately preceded this study. These findings support the food limitation hypothesis.
Kob exhibited a 4 month period of calf production during the late wet season, when food availability was highest. As a consequence, females continued lactation through the dry season period of food scarcity. I suggest that kob reproductive phenology may result from an obligatory delay during which females restore their fat reserves prior to calving or selection pressures imposed by predation during the vulnerable post-partum period.
Synchronous breeding in the Boma kob was related to
increased rates of aggression between males and increased color
dimorphism, in comparison to the asynchronous breeding Uganda kob, Kobus kob thomasi. Male aggression served not only to establish dominance relations between males on leks, but also disrupted the mating activities of neighboring males. Young adult males suffered higher age-specific mortality than females, possibly resulting from injuries incurred during strenuous fighting on leks.
In order to analyze the age structure of the kob population, I devised a new method for estimating age-specific mortality rates that is free of the restrictive assumptions that underlie most conventional techniques. The proposed method has somewhat greater sampling variation, but is considerably more robust, than two current methods. Moreover, the proposed method permits calculation of age-specific mortality at frequent intervals during periods of population fluctuation and, under some circumstances, population numerical trends may be directly determined from age structure.Science, Faculty ofZoology, Department ofGraduat
Impairment of endothelium-dependent relaxation of superior mesenteric artery in genetically diabetic WBN/Kob rats
No full text The endothelium-dependent relaxation of superior mesenteric arteries of Wistar and genetically diabetic WBN/Kob rats was compared. Endothelium-dependent relaxation induced by acetylcholine (ACh) and A23187 was depressed in WBN/Kob rats. Relaxation induced by sodium nitroprusside, an endothelium-independent agent, in strips from WBN/Kob rats was similar to that in strips from Wistar rats. Indomethacin (5 × 10−6 M) enhanced the relaxation responses to ACh in strips from both WBN/Kob and Wistar rats; however, endothelium-dependent relaxation induced by ACh remained attenuated in WBN/Kob rats. These results show that endothelium-dependent relaxation is impaired not only in thoracic aorta but also in superior mesenteric arteries in genetically diabetic rats.Key words: acetylcholine, A23187, sodium nitroprusside, indomethacin, genetically diabetic rats, endothelium-derived relaxing factor. </jats:p
Selected parasites of silver kob (Argyrosomus inodorus) (Actinopterygii: Sciaenidae) from northern Namibia
No full textThe present study reports five metazoan parasites recorded from silver kob (Argyrosomus inodorus). Five fish were collected monthly (n=55) for 11 months in 2017–2018 (excluding July 2017) using conventional angling gear in Toscanini, Mile 108 and Henties Bay, northern Namibia. Fish were examined individually for ecto- and endo-parasites. Photomicrographs, drawings and measurements of parasites were made using a camera lucida and calibrated eyepiece of an Olympus (BX50) compound microscope and/or a Zeiss (Discovery V8) camera calibrated on a Leica dissecting microscope. Amongst species found, monogeneans including Diplectanum sciaenae van Beneden & Hesse, 1863, two species of Calceostoma van Beneden, 1858, one species of Sciaenacotyle Mamaev, 1989 and one acanthocephalan Corynosoma australe Johnston, 1937 were found and are reported here. This is the first study of parasites found from silver kob of the Atlantic Ocean. Silver kob has potential to be used as a mariculture species. In addition to mariculture, information obtained from this study may also be used as a baseline for stock structure and biological tagging.
Significance: • Silver kob has potential to be used as a mariculture species. Information obtained from this study will therefore form awareness to future mariculture silver kob farmers in terms of parasites that can infest and infect silver kob, hence making it possible to apply specific prevention and control measures. In addition to mariculture, results obtained from this study may be used as a baseline for biological tagging for stock structure assessment using parasites
Toward the development of a rearing protocol for juvenile dusky kob, Argyrosomus japonicus (Pisces: Sciaenidae)
No full textThe South African mariculture industry is developing the rearing technology of indigenous fish
species. Dusky kob (Argyrosomus japonicus) has high-quality flesh and a good market demand.
Research is needed to determine the environmental requirements under which growth of dusky
kob is optimised. This study assessed the effect of temperature, light intensity, feeding frequency
and stocking density, respectively, on growth, feed conversion ratio (FCR) and survival of
juvenile dusky kob within a weight range of 10-60 g fish⁻¹) in a series of four growth trials.
The effect of temperature on growth and FCR was assessed at 14 temperatures from 17 to 28°C.
The temperature for best growth was estimated to be 25.3 °C, while 21.4 °C was the temperature
at which the best FCR was achieved. A growth trial testing the effect of light intensity on growth
showed that light intensity did not affect growth in the range of 23 – 315 lx. Fish fed a restricted
ration of 3.6% body weight per day (chapter 2) or 3.41% body weight per day (chapter 4) had a
better FCR than fish fed to satiation. A trial to assess the effect of feeding frequency on growth
and FCR showed that fish fed both two or three times daily grew better than those fed once daily.
FCR was best in fish that were fed once or twice daily. Preliminary analysis of the results from a
stocking density trial showed that stocking density in the range of 10 – 50 kg m⁻³ did not affect
growth of juvenile dusky kob.
It is recommended to culture dusky kob at a temperature of 25.3 - 21.4 °C at stocking densities
up 50 kg m⁻³ to maximise growth. However, a study is needed to determine the environmental
conditions needed to maximise profit under commercial conditions. The results allow the South
African industry the opportunity to assess the culture potential of this species. In addition, the
results will help develop protocols that can be used in other South African candidate aquaculture
species such as silver kob, yellowtail, white-stumpnose and sole
Kob-Andersen model crystal structure: genetic algorithms vs spontaneous crystallization
No full textFor the first time, the crystal structure of the Kob-Andersen mixture has been probed by genetic algorithms calculations. The stable structures of the system with different molar fractions of the components have been identified and their stability at finite temperature has been verified. A possibility to obtain these structures by spontaneous crystallization of a liquid has been checked
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