Search results for " Structures"

Entropy

2008

Starvation tolerance of rotifers produced from parthenogenetic eggs and from diapausing eggs: a life table approach

2006

Monogonont rotifers have to cope with environmental variation by producing diapausing stages.Cyclically, parthenogenetic rotifers produce females by (i) parthenogenetic eggs and (ii) sexuallyproduced eggs. Parthenogenetic eggs hatch shortly after ovoposition, frequently while they are carriedby their mothers. Sexual eggs go into dormancy and hatch in the sediment, in response to specificenvironmental cues. Therefore, it is expected that post-diapause and parthenogenetic offspring wouldface different environments. Moreover, resource allocation is higher in diapausing eggs than inparthenogenetic eggs. In this study, the response to starvation of females obtained from partheno-genetic eggs and …

Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic

2014

AbstractThe beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively)…

Hatching and viability of rotifer diapausing eggs collected from pond sediments

2006

SUMMARY 1. Planktonic rotifers inhabiting variable environments produce diapausing eggs that accumulate in the sediment of lakes and ponds, forming egg banks that may withstand adverse periods. A common assumption in zooplankton diapausing egg bank studies is to count as viable all eggs in the sediment that look healthy. This assumption should be challenged by asking how effectively ‘healthy-looking’ eggs represent viable eggs. 2. In this study, viability of more than 1100 ‘healthy-looking’ diapausing eggs belonging to the Brachionus plicatilis species complex was assessed in a laboratory hatching experiment. Eggs were collected at different depths from sediment cores obtained from 15 ponds…

Sediment Transport and Hydrodynamic Parameters of Tsunami Waves Recorded in Onshore Geoarchives

2014

In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial…

Joint brood guarding in parent bugs — an experiment on defence against predation

1995

Females of Elasmucha grisea defend their eggs and small nymphs against invertebrate predators. Females sometimes guard their clutches side by side on the same birch leaf. We studied benefits of this joint guarding both in the field and in the laboratory. We found that adjacent females had significantly larger clutches than solitary females. In the laboratory, we studied the effectiveness of joint versus single defence against ant (Formica uralensis) predators. We established female pairs from initially singly guarding females by cutting off pieces of leaves with egg clutches and pasting them beside another female guarding her clutch. In the control group the females with their clutches were…

Revisiting the Duration Dependence in the US Stock Market Cycles

2022

There is a big controversy among both investment professionals and academics regarding how the termination probability of a market state depends on its age. Using more than two centuries of data on the broad US stock market index, we revisit the duration dependence in bull and bear markets. Our results suggest that the duration dependence for both bull and bear markets is a nonlinear function of the state age. It appears that the duration dependence in bear markets is strictly positive. For 93% of the bull markets, the duration dependence is also positive. Only about 7% of the bull markets, those with the longest durations, do not exhibit positive duration dependence. We also compare a few …

The scarcity of worker cooperatives in the USA: enquiring into possible causes

2018

Even though the access of workers to capital has been promoted in some countries for over centuries, Governments and public bodies have started to promote it worldwide, as in previous occasions, more particularly as an aftermath of the Great Recession, usually in the form of worker cooperatives.However, workers’ access to capital in the USA in the form of worker cooperatives is still surprisingly rare. We cannot find any recent public policies at a federal level in order to promote them and the old ones that exist remain mostly obsolete and unknown. Only at a state and local level, we find in the latest years a series of actions directed to achieve this goal, as in the case of New York City…

Hypohidrotic Ectodermal Dysplasia with total anodontia: A case report

2011

Ectodermal dysplasia is a hereditary disorder that occurs as a consequence of disturbances in the ectoderm of the developing embryo. The triad of nail dystrophy, alopecia or hypotrichosis and palmoplantar hyperkeratosis is usually accompanied by a lack of sweat glands and a partial or complete absence of primary and/ or permanent dentition. A case report illustrating the prosthetic rehabilitation of a seven year old boy with hypohidrotic ectodermal dysplasia associated with total anodontia is presented.

Mother and offspring fitness in an insect with maternal care: phenotypic trade-offs between egg number, egg mass and egg care

2014

Background Oviparous females have three main options to increase their reproductive success: investing into egg number, egg mass and/or egg care. Although allocating resources to either of these three components is known to shape offspring number and size, potential trade-offs among them may have key impacts on maternal and offspring fitness. Here, we tested the occurrence of phenotypic trade-offs between egg number, egg mass and maternal expenditure on egg care in the European earwig, Forficula auricularia, an insect with pre- and post-hatching forms of maternal care. In particular, we used a series of laboratory observations and experiments to investigate whether these three components no…