scholarly journals Anywhere but here: local conditions motivate dispersal in Daphnia

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6599 ◽  
Author(s):  
Philip Erm ◽  
Matthew D. Hall ◽  
Ben L. Phillips
Keyword(s):  
Resource Availability ◽  
Fold Increase ◽  
Information Resource ◽  
Condition Dependence ◽  
Considerable Influence ◽  
Population Densities ◽  
Local Conditions ◽  
Current Location ◽  
Dispersal Probability ◽  
Made In

Dispersal is fundamental to population dynamics. However, it is increasingly apparent that, despite most models treating dispersal as a constant, many organisms make dispersal decisions based upon information gathered from the environment. Ideally, organisms would make fully informed decisions, with knowledge of both intra-patch conditions (conditions in their current location) and extra-patch conditions (conditions in alternative locations). Acquiring information is energetically costly, however, and extra-patch information will typically be costlier to obtain than intra-patch information. As a consequence, theory suggests that organisms will often make partially informed dispersal decisions, utilising intra-patch information only. We test this proposition in an experimental two-patch system using populations of the aquatic crustacean, Daphnia carinata. We manipulated conditions (food availability) in the population’s home patch, and in its alternative patch. We found that D. carinata made use of intra-patch information (resource availability in the home patch induced a 10-fold increase in dispersal probability) but either ignored or were incapable of using of extra-patch information (resource availability in the alternative patch did not affect dispersal probability). We also observed a small apparent increase in dispersal in replicates with higher population densities, but this effect was smaller than the effect of resource constraint, and not found to be significant. Our work highlights the considerable influence that information can have on dispersal probability, but also that dispersal decisions will often be made in only a partially informed manner. The magnitude of the response we observed also adds to the growing chorus that condition-dependence may be a significant driver of variation in dispersal.

scholarly journals Anywhere but here: local conditions alone drive dispersal in Daphnia

2018 ◽  
Author(s):  
Philip Erm ◽  
Matthew D. Hall ◽  
Ben L. Phillips
Keyword(s):  
Population Dynamics ◽  
Resource Limitation ◽  
Fold Increase ◽  
Information Resource ◽  
Condition Dependence ◽  
Local Conditions ◽  
Daphnia Carinata ◽  
Current Location ◽  
Dispersal Probability ◽  
Made In

AbstractDispersal is fundamental to population dynamics and it is increasingly apparent that, despite most models treating dispersal as a constant, many organisms make dispersal decisions based upon information gathered from the environment. Ideally, organisms would make fully informed decisions, with knowledge of both intra-patch conditions (conditions in their current location) and extra-patch conditions (conditions in alternative locations). Acquiring information is energetically costly however, and extra-patch information will typically be costlier to obtain than intra-patch information. As a consequence, theory suggests that organisms will often make partially informed dispersal decisions, utilising intra-patch information only. We test this proposition in an experimental two-patch system using populations of the aquatic crustacean, Daphnia carinata. We manipulated conditions (food availability) in the population’s home patch, and in its alternative patch. We found that D. carinata made use of intra-patch information (resource limitation in the home patch induced a ten-fold increase in dispersal probability) but made no use of extra-patch information (resource limitation in the alternative patch did not affect dispersal probability). Our work highlights the very large influence that information can have on dispersal probability, but also that dispersal decisions will often be made in only a partially informed manner. The magnitude of the response we observed also adds to the growing chorus that condition-dependence may be a significant driver of variation in dispersal.

Potential of Nanoparticles in Combating Candida Infections

2019 ◽  
Vol 16 (5) ◽  
pp. 478-491 ◽  
Author(s):  
Faizan Abul Qais ◽  
Mohd Sajjad Ahmad Khan ◽  
Iqbal Ahmad ◽  
Abdullah Safar Althubiani
Keyword(s):  
Targeted Delivery ◽  
Recent Progress ◽  
Antifungal Agents ◽  
Fungal Infections ◽  
Fold Increase ◽  
Antifungal Drugs ◽  
Low Toxicity ◽  
Candida Infections ◽  
Made In

Aims: The aim of this review is to survey the recent progress made in developing the nanoparticles as antifungal agents especially the nano-based formulations being exploited for the management of Candida infections. Discussion: In the last few decades, there has been many-fold increase in fungal infections including candidiasis due to the increased number of immunocompromised patients worldwide. The efficacy of available antifungal drugs is limited due to its associated toxicity and drug resistance in clinical strains. The recent advancements in nanobiotechnology have opened a new hope for the development of novel formulations with enhanced therapeutic efficacy, improved drug delivery and low toxicity. Conclusion: Metal nanoparticles have shown to possess promising in vitro antifungal activities and could be effectively used for enhanced and targeted delivery of conventionally used drugs. The synergistic interaction between nanoparticles and various antifungal agents have also been reported with enhanced antifungal activity.

Fate of Listeria monocytogenes During the Manufacture and Ripening of Camembert Cheese

1987 ◽  
Vol 50 (5) ◽  
pp. 372-378 ◽  
Author(s):  
ELLIOT T. RYSER ◽  
ELMER H. MARTH
Keyword(s):  
Listeria Monocytogenes ◽  
Fold Increase ◽  
Original Sample ◽  
Cheese Making ◽  
Penicillium Camemberti ◽  
Shaped Surface ◽  
Standard Procedures ◽  
Whole Milk ◽  
Camembert Cheese ◽  
Made In

The ability of Listeria monocytogenes to survive the Camembert cheese-making process and grow during ripening of the cheese was examined. Pasteurized whole milk was inoculated to contain about 500 L. monocytogenes [strain Scott A, V7, California, (CA) or Ohio (OH)] CFU/ml and made into Camembert cheese according to standard procedures. All wheels of cheese were ripened at 6°C following 10 d of storage at 15–16°C to allow proper growth of Penicillium camemberti. Duplicate wedge (pie-shaped), surface and interior cheese samples were analyzed for numbers of L. monocytogenes by surface-plating appropriate dilutions made in Tryptose Broth (TB) on McBride Listeria Agar (MLA). Initial TB dilutions were stored at 3°C and surface-plated on MLA after 2, 4, 6 or 8 weeks if the organism was not quantitated in the original sample. Selected Listeria colonies from duplicate samples were confirmed biochemically. Results showed that numbers of Listeria in cheese increased 5- to 10-fold 24 h after its manufacture. Listeria counts for strains Scott A, CA and OH decreased to <10 to 100 CFU/g in all cheese samples taken during the first 18 d of ripening. In contrast, numbers of strain V7 remained unchanged during this period. All L. monocytogenes strains initiated growth in cheese after 18 d of ripening. Maximum Listeria counts of ca. 1 × 106 to 5 × 107 CFU/g were attained after 65 d of ripening. Generally, a 10- to 100-fold increase in numbers of Listeria occurred in wedge or surface as compared to interior cheese samples taken during the latter half of ripening. During this period, Listeria growth paralleled the increase in pH of the cheese during ripening.

scholarly journals Nucleation and Grain Growth in Interstellar Space

1965 ◽  
Vol 7 ◽  
pp. 191-206
Author(s):  
Bertram Donn
Keyword(s):  
Grain Growth ◽  
Chemical Reactions ◽  
Low Temperatures ◽  
Stellar Atmospheres ◽  
Interstellar Space ◽  
Considerable Influence ◽  
Direct Bearing ◽  
Interstellar Grains ◽  
Made In

The First Detailed Studies to determine the processes by which interstellar grains may form were made by a group of Dutch astronomers in the 1940's. (See refs. 1 to 5.) Since that time very little systematic work on this problem has been done until very recently when Hoyle and Wickramasinghe (ref. 6) investigated graphite formation in cool stellar atmospheres. Van de Hulst's paper in 1949 (ref. 5) represents the culmination of an intensive attack which had considerable influence on astronomical thought about interstellar grains.Somewhat ironically, beginning about 1949 many significant advances in physics and chemistry having a direct bearing on this problem were made. In 1949, Frank in reference 7 presented a theory which explained how real crystals tend to grow, and much work, both theoretical and experimental, has been done since then. (See ref. 8.) Recent extensive research in chemical reactions at low temperatures both in solids and on surfaces is reported in reference 9.

Knowing the “Local”: Rockefeller Foundation Officers’ Site Visits to Russia in the 1920s

Slavic Review ◽  
2003 ◽  
Vol 62 (4) ◽  
pp. 710-732 ◽  
Author(s):  
Susan Gross Solomon
Keyword(s):  
Medical Education ◽  
Rockefeller Foundation ◽  
Local Conditions ◽  
Reliable Knowledge ◽  
Made In

In December 1927, Alan Gregg set off for Moscow on behalf of the Rockefeller Foundation’s Division of Medical Education to carry out a “survey of local conditions” in Soviet medical education. The visit, which had been five years in the making, was eagerly anticipated by foundation officials as the first opportunity to secure “reliable knowledge” about the new Russia. Once in the field, Gregg was confronted by important dilemmas of judgment. He had gone to Russia with a made-in-America model of medical education favored by Rockefeller Foundation officers. Was Soviet medical education a variant of the model or something radically new? In making judgments on this issue, Gregg spoke with a variety of actors involved at all levels of Soviet medical education. Which voices to credit, which to discount? Solomon examines Gregg’s landmark voyage to Russia as an instance of the challenges that face expert travelers who seek to “know” a foreign locale.

The response of sugar beet to fertilizer and the effect of farmyard manure

1962 ◽  
Vol 58 (2) ◽  
pp. 219-226 ◽  
Author(s):  
S. N. Adams
Keyword(s):  
Sugar Beet ◽  
Soil Analysis ◽  
Farmyard Manure ◽  
Mineral Fertilizer ◽  
Sugar Yield ◽  
Cereal Crops ◽  
Factorial Experiments ◽  
Local Conditions ◽  
Nitrogen Requirement ◽  
Made In

1. Forty-nine 33 factorial experiments in 1957–60 tested the response of sugar beet to 0·6,1·2, 1·8 cwt. N, 0·0,0·5,1·0 cwt. P2O5 and 0·8 1·6 2·4 cwt. K2O per acre. On forty-one of the sites, the experiment was repeated in the presence of 12 tons FYM per acre. There were also six trials in which the rates of mineral fertilizer had been altered to suit local conditions.2. Optimum dressings for sugar yield without FYM were 1·0 cwt. N, 0·5 cwt. P2O6 and 1·6 cwt. K2O per acre. This closely agrees with results of experiments made in 1934–39. Exceeding the optimum nitrogen dressing decreased sugar yield although the yield of tops was increased. The main value of dung for beet was in the N, P and K it provided. With FYM, optimum dressings were only 0·6 cwt. N, 0·0 cwt. P2O5 and 0·8 cwt. K2O per acre.3. Response to nitrogen differed greatly from field to field and the best guide to the nitrogen requirement of a field was the previous cropping. Beet which followed two or more cereal crops needed more nitrogen on average than beet which did not. Response to phosphate and potash did not differ much in different experiments and the national optimum would have been satisfactory for nearly all fields. The only use of soil analysis was to identify the very few fields which needed more than the average dressing of phosphate. The efficiency of phosphate and potash manuring could be slightly increased by taking soil type into account.

The Termites of the Solomon Islands

1958 ◽  
Vol 49 (4) ◽  
pp. 737-750 ◽  
Author(s):  
W. V. Harris ◽  
E. S. Brown
Keyword(s):  
Relative Abundance ◽  
Solomon Islands ◽  
Control Measures ◽  
Local Conditions ◽  
Made In

Twelve species of termites occurring in the British Solomon Islands Protectorate are listed, and an illustrated key to their soldier castes is provided. An analysis of the 114 records has been made in order to indicate, in a general way, the relative abundance of the various species. Notes are given on distribution within the islands, on habitats and nests, and on the occurrence of termites on coconut palms and in buildings. Damage to buildings is discussed and suggestions made for control measures applicable to local conditions.

Geographic Inequity in the Availability of Cognitive Behavioural Therapy in England and Wales: A 10-Year Update

2013 ◽  
Vol 42 (4) ◽  
pp. 497-501 ◽  
Author(s):  
Kate Cavanagh
Keyword(s):  
Cognitive Behavioural Therapy ◽  
Geographic Distribution ◽  
Fold Increase ◽  
Behavioural Therapy ◽  
England And Wales ◽  
Psychological Therapies ◽  
Cognitive Behavioural ◽  
Proxy Measure ◽  
Scarcity Of Resources ◽  
Made In

Background: Improving access to psychological therapies, and in particular cognitive behavioural therapy (CBT), has been a health service priority in England and Wales over the past decade. The delivery of CBT has been limited by a scarcity of resources and further limited by the inequitable geographic distribution of CBT therapists. Aims: The current study replicates and extends our previous analysis of the geography of British Association of Behavioural and Cognitive Psychotherapies (BABCP) membership (Shapiro, Cavanagh and Lomas, 2003) 10 years later in order to evaluate the progress made in improving equitable access to CBT. Method: This paper presents the absolute and comparative geographic distribution of current BABCP members, accredited CBT practitioners, and BABCP members who are nurses or clinical psychologists in England and Wales. Results: Efforts to improve the availability of CBT in England and Wales are reflected in the doubling of total membership, and a 4.5 fold increase in accredited membership over the last 10 years. There is evidence that the magnitude of inequity in the geographic availability of CBT therapists has decreased, but that inequity is still evident. Limitations of using BABCP membership data as a proxy measure of CBT availability are acknowledged. Conclusions: A five-fold discrepancy in accredited CBT practitioners between the best and least well-served population decile indicates ongoing “postcode availability” of the best qualified CBT practitioners. Possible strategies to improve the availability of CBT and remedy this inequity are discussed.

Vegetation structure and ungulate abundance over a period of increasing elephant abundance in Hwange National Park, Zimbabwe

2007 ◽  
Vol 23 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Marion Valeix ◽  
Hervé Fritz ◽  
Ségolène Dubois ◽  
Kwanele Kanengoni ◽  
Samuel Alleaume ◽  
...  
Keyword(s):  
Vegetation Structure ◽  
National Park ◽  
Fold Increase ◽  
Landscape Scale ◽  
Aerial Photographs ◽  
Population Densities ◽  
Elephant Population ◽  
Negative Effect ◽  
Herbivore Species ◽  
Hwange National Park

This study investigates whether increases in elephant populations may influence the structure of African savannas, and consequently may affect other herbivores through changes in habitats. Two contrasting periods in terms of elephant population densities were compared in Hwange National Park, Zimbabwe: the early 1980s and the late 1990s. Elephant population density and other ungulate population densities were estimated for a c. 400-km2 area from road counts. Vegetation structure at the landscape scale was assessed using aerial photographs for the same area. All browsers and grazers declined between the early 1980s and the late 1990s, whereas elephants experienced a 16-fold increase. At the landscape scale, vegetation structure changed little with no evidence of an opening of the habitats. These results do not support any kind of medium-term facilitation between elephants and other herbivores. They rather suggest a negative effect of elephants on other herbivore species when elephants are present at high densities. This study rules out a scenario where the decrease of the different herbivore populations was caused by large changes in vegetation structure due to elephant activity.

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