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Ecology and Evolution Jun 2023For many species, estimating density is challenging, but it is important for conservation planning and understanding the functional role of species. Bats play key...
For many species, estimating density is challenging, but it is important for conservation planning and understanding the functional role of species. Bats play key ecological roles, yet little is known about their free-ranging density. We used a long-term banding study of four species caught in an extensively forested climate refuge and spatial capture-recapture models (SCR) to estimate density and its change over time. Between 1999 and 2020, there were 3671 captures of four bat species, which were all edge-space foragers. Recaptures represented 16% ( = 587) of all captures, of which 89 were between-trap-cluster movements. Closed spatial mark-recapture models estimated plausible densities that varied with elevation. Preferred elevations differed between species, with density averaging 0.63 ha for (high elevation), 0.43 ha for (low elevation), 0.19 ha for (high elevation), and 0.08 ha for (high elevation). Overall, densities were higher than most previous published estimates for bats. Forest disturbance history (past timber harvesting) had no detectable effect on density. Density also varied substantially across years, and although annual maximum temperature and rainfall were not supported in models, some time periods showed an apparent relationship between density and annual rainfall (+ve) and/or annual maximum temperature (-ve). The most notable change was an increase in the density of after 2013, which tracked an increase in annual temperature at the site, reflecting a warming climate. Bat densities in forests outside of climate refugia are likely to be more sensitive to climate change, but more studies are needed in different habitats and continents and outside climate refugia to place the densities we estimated into a broader context.
PubMed: 37332522
DOI: 10.1002/ece3.10215 -
Poultry Science Jul 2023This experiment was conducted to study the effect of housing systems and housing densities on the performance and digestive tract growth of broiler chicks during the...
This experiment was conducted to study the effect of housing systems and housing densities on the performance and digestive tract growth of broiler chicks during the first 2 wk of age. A total of 3,600 Cobb500 day-old chicks were stocked at 4 densities (30, 60, 90, and 120 chicks/m), and reared under 2 housing systems (conventional housing system and newly developed housing system), yielding a 2 × 4 factorial arrangement. The studied traits were performance, viability, and gastrointestinal tract development. The results indicated that housing systems and housing densities significantly (P < 0.001) affected the performance and GIT development of chicks. There were no significant interactions between housing system and housing density for body weight, body weight gain, feed intake, and feed conversion. The results also showed that the effects of housing density were age-dependent. That is, the higher the density, the lower the performance and digestive tract growth with advancing age. In conclusion, birds in the conventional system outperformed birds in the newly developed housing system, and further work is needed to improve the new housing system. To achieve the highest performance, digestive tract growth, and digesta content, a density of 30 chicks/m is recommended for chicks up to 14-days old.
Topics: Animals; Animal Feed; Body Weight; Chickens; Diet; Eating; Gastrointestinal Tract; Housing, Animal
PubMed: 37245440
DOI: 10.1016/j.psj.2023.102752 -
Advanced Science (Weinheim,... Jul 2021Lithium-sulfur (Li-S) batteries, as part of the post-lithium-ion batteries (post-LIBs), are expected to deliver significantly higher energy densities. Their power...
Lithium-sulfur (Li-S) batteries, as part of the post-lithium-ion batteries (post-LIBs), are expected to deliver significantly higher energy densities. Their power densities, however, are today considerably worse than that of the LIBs, limiting the Li-S batteries to very few specific applications that need low power and long working time. With the rapid development of single cell components (cathode, anode, or electrolyte) in the last few years, it is expected that an integrated approach can maximize the power density without compromising the energy density in a Li-S full cell. Here, this goal is achieved by using a novel biomass porous carbon matrix (PCM) in the anode, as well as N-Co S nanoparticles and carbon nanotubes (CNTs) in the cathode. The authors' approach unlocks the potential of the electrodes and enables the Li-S full pouch cells with unprecedented power densities and energy densities (325 Wh kg and 1412 W kg , respectively). This work addresses the problem of low power densities in the current Li-S technology, thus making the Li-S batteries a strong candidate in more application scenarios.
PubMed: 34032382
DOI: 10.1002/advs.202101182 -
Gaceta Medica de Mexico 2021Different optical coherence tomography angiography (OCTA) scanning protocols evaluate the macula. (Comparative Study)
Comparative Study Observational Study
INTRODUCTION
Different optical coherence tomography angiography (OCTA) scanning protocols evaluate the macula.
OBJECTIVE
To compare the determination coefficients (R) between vessel and perfusion densities of two OCTA scanning protocols in order to determine if their metrics could be interchanged.
METHOD
Cross-sectional, prospective, comparative, observational, study between two OCTA scanning protocols (Angioplex, Zeiss) in healthy subjects. The R between central, inner, and full densities (3 x 3 mm protocol) and between central, inner, outer and full densities (6 x 6 mm protocol) was identified, both for vessel and perfusion densities.
RESULTS
Seventy-eight eyes were evaluated; subjects' median age was 23 years. There were high R between inner and full densities with the 3 x 3 mm protocol (0.96), between outer and full densities with the 6 x 6 mm protocol (0.96), and between central vessel and perfusion densities (≥ 0.96); R between central vessel and perfusion densities of different protocols was ≤ 0.71.
CONCLUSIONS
Vessel and perfusion densities have high determination coefficients within a scanning protocol, but not between protocols, given that each one preferentially measures different macular areas. Metrics from different protocols should not be interchanged for follow up.
Topics: Adult; Angiography; Blood Vessels; Cross-Sectional Studies; Female; Healthy Volunteers; Humans; Macula Lutea; Male; Prospective Studies; Regional Blood Flow; Statistics, Nonparametric; Tomography, Optical Coherence; Visual Acuity; Young Adult
PubMed: 34270531
DOI: 10.24875/GMM.20000471 -
PeerJ 2021The conservation of large carnivores often requires precise and accurate estimates of their populations. Being cryptic and occurring at low population densities,...
The conservation of large carnivores often requires precise and accurate estimates of their populations. Being cryptic and occurring at low population densities, obtaining an unbiased population estimate is difficult in large carnivores. To overcome the uncertainties in the conventional capture-recapture (CR) methods used to estimate large carnivore densities, more robust methods such as spatially explicit capture-recapture (SECR) framework are now widely used. We modeled the CR data of tiger () and leopard () in the SECR framework with biotic and abiotic covariates likely believed to influence their densities. An effort of 2,211 trap nights resulted in the capture of 33 and 38 individual tigers and leopards. A total of 95 and 74 detections of tigers and leopards were achieved using 35 pairs of camera traps. Tiger and leopard density were estimated at 4.71 ± 1.20 (3.05-5.11) and 3.03 ± 0.78 (1.85-4.99) per 100 km. Our results show that leopard density increased with high road density, high terrain ruggedness and habitats with high percentage of cropland and natural vegetation. The tiger density was positively influenced by the mosaic of cropland and natural vegetation. This study provides the first robust density estimates of tiger and leopard within the study area. Our results support the notion that large carnivores can attain moderate densities within human-dominated regions around protected areas relying on domestic livestock. Broader management strategies aimed at maintaining wild prey in the human-dominated areas around protected areas are necessary for large and endangered carnivores' sustenance in the buffer zones around protected areas.
PubMed: 33643701
DOI: 10.7717/peerj.10634 -
Ecology and Evolution Oct 2022Scavenging is widespread in the carnivore guild and can greatly impact food web structures and population dynamics by either facilitation or suppression of sympatric...
Scavenging is widespread in the carnivore guild and can greatly impact food web structures and population dynamics by either facilitation or suppression of sympatric carnivores. Due to habitat loss and fragmentation, carnivores are increasingly forced into close sympatry, possibly resulting in more interactions such as kleptoparasitism and competition. In this paper, we investigate the potential for these interactions when carnivore densities are high. A camera trap survey was conducted in central Tuli, Botswana, to examine leopard densities and spatiotemporal activity patterns of leopard and its most important competitors' brown hyena and spotted hyena Spatial capture-recapture models estimated leopard population density to be 12.7 ± 3.2 leopard/100 km, which is one of the highest leopard densities in Africa. Time-to-event analyses showed both brown hyena and spotted hyena were observed more frequently before and after a leopard observation than expected by chance. The high spatiotemporal overlap of both hyena species with leopard is possibly explained by leopard providing scavenging opportunities for brown hyena and spotted hyena. Our results suggest that central Tuli is a high-density leopard area, despite possible intense kleptoparasitism and competition.
PubMed: 36225822
DOI: 10.1002/ece3.9365 -
PloS One 2022Broiler production in semi-arid tropics must contend with high levels of heat stress, which have implications on stocking density, bird welfare, and profitability. Under...
Stocking density-induced changes in growth performance, blood parameters, meat quality traits, and welfare of broiler chickens reared under semi-arid subtropical conditions.
Broiler production in semi-arid tropics must contend with high levels of heat stress, which have implications on stocking density, bird welfare, and profitability. Under these conditions, optimal stocking densities are likely to be lower than expected, thus must be experimentally determined. Therefore, this study investigated growth performance, haematology, serum biochemistry, carcass and meat quality, sizes of internal organs, and stress biomarkers in response to different stocking densities in broilers reared under semi-arid subtropical conditions. Five hundred, day-old Ross 308 broilers (44.0 ± 5.24 g live-weights) were randomly distributed to 25 replicate pens (1.32 m2 floor space each) to create five stocking densities: 1) 10 birds/pen (SD10); 2) 15 birds/pen (SD15); 3) 20 birds/pen (SD20); 4) 25 birds/pen (SD25); and 5) 30 birds/pen (SD30). There was a linear decrease (P < 0.05) in overall feed intake and weight gain in weeks 2 and 3 as stocking density increased. However, weight gain showed positive and negative quadratic responses (P < 0.05) in weeks 5 and 6, respectively, as stocking density increased. No linear or quadratic effects (P ˃ 0.05) were observed for overall feed conversion ratio, haematological parameters, and meat quality traits in response to stocking density. Symmetric dimethylarginine, alanine transaminase, and albumin levels quadratically increased (P < 0.05) in response to increasing stocking densities. Serum glucose and thigh weight were not affected (P < 0.05) while final body, drumstick, breast, and wing weights linearly declined with stocking density. Increasing stocking density linearly reduced (P < 0.05) the weights of gizzard, proventriculus, caecum, and colon. Stocking density had no effect (P ˃ 0.05) on latency-to-lie. It was concluded that higher stocking densities compromised feed intake, resulting in poor weight gains. Based on weight gain trends observed in week 5, it was determined that Ross 308 broilers should be reared at no more than 20 birds/pen (~15 birds/m2 or 27.27 kg/m2) under the experimental ambient conditions compared to the much higher globally accepted industry standard of 20 birds/m2.
Topics: Alanine Transaminase; Albumins; Animal Husbandry; Animals; Biomarkers; Chickens; Glucose; Meat; Weight Gain
PubMed: 36227929
DOI: 10.1371/journal.pone.0275811 -
Clinical & Experimental Optometry Nov 2020The aim of this study was to compare the macular and peripapillary vessel densities in eyes of young Chinese adults with different degrees of myopia and to evaluate the...
BACKGROUND
The aim of this study was to compare the macular and peripapillary vessel densities in eyes of young Chinese adults with different degrees of myopia and to evaluate the association of macular and peripapillary vessel densities with axial length and retinal nerve fibre layer thickness.
METHODS
A total of 128 eyes (mild myopia, 42; moderate myopia, 45; severe myopia, 41) underwent optical coherence tomography angiography imaging. Parameters assessed were vessel densities in the superficial capillary plexus and deep capillary plexus of the macular area, peripapillary vessel density, retinal nerve fibre layer thickness, foveal thickness and foveal avascular zone area (mm ).
RESULTS
Vessel densities in the macular and peripapillary areas as well as peripapillary retinal nerve fibre layer thickness decreased significantly when comparing high myopia to mild myopia. Axial length was significantly associated with vessel density in the macular area (superficial capillary plexus: r = -0.249, p = 0.008; deep capillary plexus: r = -0.398, p < 0.001), peripapillary area (r = -0.204, p = 0.028), foveal avascular zone area (r = -0.309, p < 0.001), and foveal thickness (r = 0.354, p < 0.001). Negative correlations were found between axial length and peripapillary vessel density as well as retinal nerve fibre layer thickness at the nasal superior, nasal inferior and inferior nasal quadrants.
CONCLUSION
Varying degrees of myopia affected macular and peripapillary vessel densities as well as retinal nerve fibre layer thickness in young healthy adults. The high myopic group had the lowest vessel density in the superficial capillary plexus, deep capillary plexus of the macular area and the peripapillary area. With increased axial length, macular and peripapillary vessel densities, retinal nerve fibre layer thickness and foveal avascular zone area reduced while foveal thickness increased.
Topics: Adult; China; Humans; Macula Lutea; Myopia; Retinal Vessels; Tomography, Optical Coherence
PubMed: 32052475
DOI: 10.1111/cxo.13047 -
Journal of Applied Microbiology Jul 2008To determine the wet and dry density of spores of Bacillus anthracis and compare these values with the densities of other Bacillus species grown and sporulated under... (Comparative Study)
Comparative Study
AIMS
To determine the wet and dry density of spores of Bacillus anthracis and compare these values with the densities of other Bacillus species grown and sporulated under similar conditions.
METHODS AND RESULTS
We prepared and studied spores from several Bacillus species, including four virulent and three attenuated strains of B. anthracis, two Bacillus species commonly used to simulate B. anthracis (Bacillus atrophaeus and Bacillus subtilis) and four close neighbours (Bacillus cereus, Bacillus megaterium, Bacillus thuringiensis and Bacillus stearothermophilus), using identical media, protocols and instruments. We determined the wet densities of all spores by measuring their buoyant density in gradients of Percoll and their dry density in gradients of two organic solvents, one of high and the other of low chemical density. The wet density of different strains of B. anthracis fell into two different groups. One group comprised strains of B. anthracis producing spores with densities between 1.162 and 1.165 g ml(-1) and the other group included strains whose spores showed higher density values between 1.174 and 1.186 g ml(-1). Both Bacillus atrophaeus and B. subtilis were denser than all the B. anthracis spores studied. Interestingly and in spite of the significant differences in wet density, the dry densities of all spore species and strains were similar. In addition, we correlated the spore density with spore volume derived from measurements made by electron microscopy analysis. There was a strong correlation (R(2) = 0.95) between density and volume for the spores of all strains and species studied.
CONCLUSIONS
The data presented here indicate that the two commonly used simulants of B. anthracis, B. atrophaeus and B. subtilis were considerably denser and smaller than all B. anthracis spores studied and hence, these simulants could behave aerodynamically different than B. anthracis. Bacillus thuringiensis had spore density and volume within the range observed for the various strains of B. anthracis. The clear correlation between wet density and volume of the B. anthracis spores suggest that mass differences among spore strains may be because of different amounts of water contained within wet dormant spores.
SIGNIFICANCE AND IMPACT OF THE STUDY
Spores of nonvirulent Bacillus species are often used as simulants in the development and testing of countermeasures for biodefense against B. anthracis. The similarities and difference in density and volume that we found should assist in the selection of simulants that better resemble properties of B. anthracis and, thus more accurately represent the performance of countermeasures against this threat agent where spore density, size, volume, mass or related properties are relevant.
Topics: Bacillus anthracis; Bacillus cereus; Bacillus subtilis; Bacillus thuringiensis; Bacteriological Techniques; Geobacillus stearothermophilus; Microscopy, Electron, Transmission; Spores, Bacterial
PubMed: 18298528
DOI: 10.1111/j.1365-2672.2008.03758.x -
Scientific Reports May 2022Intercellular induction of apoptosis (IIA) represents a well-defined signaling model by which precancerous cells are selectively eradicated through reactive...
Intercellular induction of apoptosis (IIA) represents a well-defined signaling model by which precancerous cells are selectively eradicated through reactive oxygen/nitrogen species and cytokine signaling from neighbour normal cells. Previously, we demonstrated that the IIA process could be enhanced by exposure of normal cells to very low doses of ionizing radiation as a result of perturbing the intercellular signaling. In this study, we investigate the kinetic behaviour of both autocrine destruction (AD) and IIA as a function of cell density of both precancerous and normal cells using an insert co-culture system and how exposure of normal cells to ionizing radiation influence the kinetics of apoptosis induction in precancerous cells. Increasing the seeding density of transformed cells shifts the kinetics of AD towards earlier times with the response plateauing only at high seeding densities. Likewise, when co-culturing precancerous cells with normal cells, increasing the seeding density of either normal or precancerous cells also shifts the kinetics of IIA response towards earlier times and plateau only at higher seeding densities. Irradiation of normal cells prior to co-culture further enhances the kinetics of IIA response, with the degree of enhancement dependent on the relative cell densities. These results demonstrate the pivotal role of the cell seeding density of normal and precancerous cells in modulating both AD and IIA. These results further support the proposition that ionizing radiation could result in an enhancement in the rate of removal of precancerous cells through the IIA process.
Topics: Apoptosis; Cell Count; Humans; Kinetics; Precancerous Conditions; Radiation, Ionizing; Reactive Nitrogen Species; Reactive Oxygen Species
PubMed: 35505194
DOI: 10.1038/s41598-022-11253-1