Fluctuations In Ratios Research Articles

Frequency-dependent selection acting on the widely fluctuating sex ratio of the aphid Prociphilus oriens.

Frequency-dependent selection is a fundamental principle of adaptive sex ratio evolution in all sex ratio theories but has rarely been detected in the wild. Through long-term censuses, we confirmed large fluctuations in the population sex ratio of the aphid Prociphilus oriens and detected frequency-dependent selection acting on these fluctuations. Fluctuations in the population sex ratio were partly attributable to climatic factors during the growing season. Climatic factors likely affected the growth conditions of host plants, which in turn led to yearly fluctuations in maternal conditions and sex ratios. In the process of frequency-dependent selection, female proportion higher or lower than ca. 60% was associated with a reduction or increase in female proportion, respectively, the next year. The rearing of aphid clones in the laboratory indicated that mothers of each clone produced an increasing number of females as maternal size increased. However, the mean male number was not related to maternal size, but varied largely among clones. Given genetic variance in the ability to produce males among clones, selection should favour clones that can produce more numerous males in years with a high female proportion. Population-level sex allocation to females was on average 71%-73% for three localities and more female-biased when maternal conditions were better. This tendency was accounted for by the hypothesis of competition among foundresses rather than the hypothesis of local mate competition. We conclude that despite consistent operation of frequency-dependent selection, the sex ratio continues to fluctuate because environmental conditions always push it away from equilibrium.

Comparative Analysis of Profitability of Local and Foreign Banks in Ghana

The implementation of the Financial Sector Adjustment Programme has beckoned to a number of foreign banks to flock into the country to do business. This has brought about intense competition in the banking industry with its attendant implications for profitability in the industry. In the light of this, the study seeks to make a comparative analysis of the profitability of foreign and local banks in Ghana. The study uses a sample of six banks of which three are foreign banks. Financial statements of the selected banks from 2008 to 2014 are used for the analysis employing profitability ratios such as Return on Assets (ROA), Capital Adequacy (CA), Return on Equity (ROE) and Management Efficiency (ME). We find wide fluctuations in the profitability ratios of the banks. Again, the foreign banks are found to have outperformed the local banks in ROA, CA and ROE. The local banks however, performed better than the foreign banks in ME, except in 2009. We conclude that, the foreign banks are more profitable than their local counterparts during the period under study. It is therefore recommended that, protective measures be put in place to make the local banks more competitive. For instance, the local banks could be required to make less minimum capital requirements than the foreign banks.

Cell‐to‐cell variability of alternative RNA splicing

Heterogeneity in the expression levels of mammalian genes is large even in clonal populations and has phenotypic consequences. Alternative splicing is a fundamental aspect of gene expression, yet its contribution to heterogeneity is unknown. Here, we use single-molecule imaging to characterize the cell-to-cell variability in mRNA isoform ratios for two endogenous genes, CAPRIN1 and MKNK2. We show that isoform variability in non-transformed, diploid cells is remarkably close to the minimum possible given the stochastic nature of individual splicing events, while variability in HeLa cells is considerably higher. Analysis of the potential sources of isoform ratio heterogeneity indicates that a difference in the control over splicing factor activity is one origin of this increase. Our imaging approach also visualizes non-alternatively spliced mRNA and active transcription sites, and yields spatial information regarding the relationship between splicing and transcription. Together, our work demonstrates that mammalian cells minimize fluctuations in mRNA isoform ratios by tightly regulating the splicing machinery.

Alternative splicing variability: exactly how similar are two identical cells?

Alternative splicing variability: exactly how similar are two identical cells?

Is the Special Purpose Vehicles Act Responsible for the Decline in NPL Ratios?

Normal 0 false false false MicrosoftInternetExplorer4 This study aimed to determine if the SPV Act was actually responsible for the marked decline in NPL ratios this past four years. Using aggregated data for the entire Philippine Banking System, segregated according to type of bank, results suggest that the SPV Act was not responsible for the decline in the NPL ratios but may be attributed to a downward trend in the loan to asset ratio where values are getting closer to the interval for which NPL ratios are at a minimum, economic sluggishness as measured by deviations from the long run trend of macroeconomic variables, and seasonal patterns in macroeconomic variables coinciding with fluctuations in NPL ratios.

The Impact of Positive and Negative Mood on the Hypothesis Generation and Ethical Judgments of Auditors

SUMMARY: This paper examines the impact of mood on the hypothesis generation and ethical judgments of auditors. Prior psychology research documents different effects of negative and positive mood on information processing such that negative (positive) mood leads to more systematic (heuristic) processing (e.g., Forgas 1995a; Bless 2000). Theoretical accounting research (Gaudine and Thorne 2001) proposes a positive relation between positive mood and ethical decision-making. Based on this research, we predict that negative (compared with positive) mood will enhance performance on a hypothesis generation task and impair performance on two ethical tasks. These predictions are tested in an experiment in which auditors perform an analytical procedures task involving the generation of explanations for fluctuations in financial ratios and two ethical tasks involving the truthful reporting of information. Consistent with predictions, the results show that auditors' judgments are influenced by their mood state. Specifically, auditors in a negative (compared with a positive) mood generated more correct explanations for fluctuations in financial ratios, but made less ethical judgments. The implications of these results are discussed, and suggestions for future research are offered.

Pulsatory magma supply to a phonolite lava lake

A few lava lakes, like that at Erebus volcano, Antarctica, have been continuously active for decades, reaching a steady-state. We report spectroscopic and thermal observations from Erebus that reveal remarkable, phase-locked cycles of lava lake convection and gas plume composition. We argue that the observed fluctuations in gas ratios, including the SO 2/CO 2 content in the plume, identify two end-member contributions to the Erebus emission: a sustained source of CO 2-rich gas percolating through permeable conduit magma, and a shallower source of H 2O-rich gas exsolved from magma pulses that periodically enter the lava lake. The unstable magma flow may reflect the viscosity stratification between rising and descending magma in the conduit, and the resulting oscillatory behaviour of the phonolite lake exemplifies the relative roles of closed- and open-system degassing in persistently active volcanoes.

Unique Inbred Strain MSM/Ms Established from the Japanese Wild Mouse

Most laboratory mice belong to a species of house mouse, Mus musculus. So far, at least three subspecies groups have been recognized; domesticus subspecies group (DOM) distributed in western Europe, musculus subspecies group (MUS) distributed in eastern Europe and northeast Asia, and castaneus subspecies group (CAS) found in southwest and southeast Asia including southern China. These subspecies are estimated to have branched off roughly one million years ago. Genetic comparison between subspecies' groups and common inbred strains (CIS) have revealed that the genetic background of CIS is derived mainly from DOM. This shows the importance of non-DOM wild mice as valuable genetic resources. We started to establish our unique strain, MSM/Ms, from MUS in Japan in 1978. In the beginning, we kept wild mice trapped in Mishima in large plastic buckets. In 1979, breeding by sister-brother mating started. The MSM/Ms inbred strain was established in 1986 and 21 years later it reached F(100). During breeding, no significant fluctuations in litter size and sex ratios have been observed. Extensive genetic analyses of chromosome C-banding pattern, biochemical markers and microsatellite DNA (MIT) markers of this strain have demonstrated the characteristics of MUS. A phylogenetic tree constructed from MIT markers has confirmed the MUS nature of MSM strain. Taken together with its genetic remoteness from CIS, MSM appears to maintain many valuable alleles for investigation of biological functions and diseases. Some of these alleles have avoided selection during breeding as either fancy mice or laboratory mice. The MSM-specific genetic traits discovered to date are discussed.

Climate effects on offspring sex ratio in a viviparous lizard

1. Understanding individual and population responses to climate change is emerging as an important challenge. Because many phenotypic traits are sensitive to environmental conditions, directional climate change could significantly alter trait distribution within populations and may generate an evolutionary response. 2. In species with environment-dependent sex determination, climate change may lead to skewed sex ratios at hatching or birth. However, there are virtually no empirical data on the putative link between climatic parameters and sex ratios from natural populations. 3. We monitored a natural population of viviparous lizards with temperature-dependent sex determination (Niveoscincus ocellatus) over seven field seasons. Sex ratios at birth fluctuated significantly among years and closely tracked thermal conditions in the field, with the proportion of male offspring increasing in colder years. 4. This is the first study to demonstrate the effect of local climatic conditions (e.g. temperature) on offspring sex ratio fluctuations in a free-living population of a viviparous ectotherm. A succession of warmer-than-usual years (as predicted under many climate-change scenarios) likely would generate female-biased sex ratios at birth, while an increase in interannual variation (as also predicted under climate change scenarios) could lead to significant fluctuations in cohort sex ratios. If cohort sex ratio bias at birth leads to adult sex ratio bias, long-term directional changes in thermal conditions may have important effects on population dynamics in this species.

Dinucleotide-Sensing Proteins: Linking Signaling Networks and Regulating Transcription

Differential binding of dinucleotides to key regulatory proteins can modulate their interactions with other proteins and, in some cases, can signal fluctuations in the cellular redox state, to produce changes in transcription and physiological state. The dinucleotide-binding proteins human HSCARG and yeast transcription repressor Gal80p are examples that offer exciting glimpses into the potential for dinucleotide-sensing proteins to couple fluctuations in dinucleotide ratios to changes in transcription and to act as networking agents linking different classes of signaling molecules.

Climate influence on geochemistry parameters of waters from Santana–Pérolas cave system, Brazil

A four-year study of water geochemistry and hydrology was performed in a relatively deep cave system (overlying bedrock thickness varies from 100 to 300 m) as part of two monitoring programs, from June 1990 to February 1992 and from March 2000 to March 2002. The pH, saturation index for calcite, Ca and SO 4 concentrations, and elemental ratios of Mg/Ca and Sr/Ca were measured in surface, well and drip waters throughout the system. Despite local hydrological and geological differences among sampling sites, the monitoring revealed significant synchronous intersite variations in these parameters that are related to seasonal changes in rainfall recharge, suggesting that element ratios of speleothems formed in deep caves are capable of recording short-term climate variations. Groundwater residence time appears to be the main factor affecting the water composition in the epikarst. Epikarstic waters are always undersaturated with respect to calcite but both saturation index (S.I.) and dissolved solids content increase substantially during drier periods because of longer residence times and longer interaction between meteoric water and limestone. By contrast, results from cave drips and rimstone pools indicate constant supersaturation for calcite and demonstrate that a major control on trace element ratios of waters in the deep vadose zone is the degree of prior calcite precipitation. This mechanism is more effective during drier periods when higher Mg/Ca and Sr/Ca values are observed in all drip and pool sites. However, variations do occur independently of the general trend of drip discharge, which suggest non-linear features in cave seepage water geochemistry. In addition, synchronous variations in SO 4 and Cl concentration indicate high connectivity between different water flow pathways characterized by similar response to interseasonal changes in vadose water level. Fluctuations in trace element ratios of cave streams appear to reflect increased contribution of waters flushed from the vadose fissure aquifer during very wet periods by a piston flow mechanism. Flushing episodes are also responsible for maintaining more positive saturation indices in streams even during periods of high river discharge. Our results suggest that trace elements are a potential proxy for past rainfall changes but they also reveal different scenarios for interpreting trace elements ratios of speleothems and freshwater tufa deposited in a deep cave systems located in tropical humid areas.

Flow, mixing, and displacement in using a data‐based hydrochemical model to predict conservative tracer data

We extend the data‐based hydrochemical model of Iorgulescu et al. (2005), able to simulate discharge and reactive chemical tracer concentrations (silica and calcium) in streamflow for subcatchments of the Haute‐Mentue research basin (Switzerland), to the prediction of additional δ18O values treated as a conservative tracer. The hydrochemical model is based on a parameterization of three runoff components (direct precipitation (DP), acid soil water (AS), and deep groundwater (GW)) in a chemical mixing model. Each component is modeled through an identical structure consisting of a nonlinear gain and a linear transfer function with two reservoirs (fast/slow) in parallel having a constant partition between them. We formulate a set of hypotheses concerning the isotope characterization of each component to provide additional information about how new rainfall inputs are processed in the hydrological response of the catchment. In particular, the AS component is modeled through a nested structure of hypotheses (models) of increasing complexity. It will be shown that hydrological processes in the hillslope associated with the DP, AS, and GW components are especially effective in filtering of higher‐frequency fluctuations in precipitation isotopic ratios at the intraevent, interevent/seasonal, and annual/multiannual timescales. The highly nonlinear and nonstationary AS component represents predominantly “recent” water stored in the upper decimeters of the soil profile. Results also suggest that subsurface pathways are significant for the DP component. A local flow path mechanism is proposed for explaining the large fluxes of subsurface flows.

Comparisons of statistical multifragmentation and evaporation models for heavy-ion collisions

The results from ten statistical multifragmentation models have been compared with each other using selected experimental observables. Even though details in any single observable may differ, the general trends among models are similar. Thus, these models and similar ones are very good in providing important physics insights especially for general properties of the primary fragments and the multifragmentation process. Mean values and ratios of observables are also less sensitive to individual differences in the models. In addition to multifragmentation models, we have compared results from five commonly used evaporation codes. The fluctuations in isotope yield ratios are found to be a good indicator to evaluate the sequential decay implementation in the code. The systems and the observables studied here can be used as benchmarks for the development of statistical multifragmentation models and evaporation codes.

Children in European systems of slavery: Introduction

This special edition on children in western systems of slavery1 follows last year's special edition of Slavery & Abolition on women in western systems of slavery in moving beyond the conventional t...

Stoichiometric mismatch between littoral invertebrates and their periphyton food

Abstract: Ecological stoichiometry is considered a key concept in understanding con-straints in energy transfer at the plant-herbivore interface. However, whether this con-cept is relevant for benthic freshwater ecosystems is not fully known. Therefore, afield survey was conducted in 2003 during the growing season in the littoral zone ofLake Constance, a large pre-alpine lake in central Europe. The aim was to assess tem-poral variation in the elemental stoichiometric composition in both herbivorous macro-invertebrates and their food resource, the periphyton in two different lakes. The peri-phyton showed large temporal and spatial variation in carbon, nitrogen, and phospho-rus content, with particularly high molar C:P ratios of up to 1225:1. Periphyton C:Pand C:N ratios were often high and constantly above the Redfield ratio that is consid-ered optimal for autotrophic growth. In contrast to the pronounced fluctuations in thenutrient ratios of their food resource, the herbivorous macroinvertebrates showed onlyvery little variation in their nutrient ratios, which indicated that they are homeostatic,i.e., physiologically restricted to a comparatively narrow range of C:P and C:N ratios.Distinct species-specific C : P and C : N ratios were found for different taxonomicgroups of macroinvertebrates, which indicated different requirements of optimal die-tary C:P and C:N ratios and which might influence the ability of the taxa to competefor limiting elemental nutrients. Considering the temporally very high C:P and C:Nratios of the periphytic resource and the very low ratios of the consumer body tissue,this stoichiometric mismatch is likely to constrain growth and reproduction of these lit-toral invertebrates. Therefore, the concept of stoichiometric food quality limitationmight also be applicable to the littoral food web in lakes.Key words: benthos, C:N:P ratio, ecological stoichiometry, herbivory, homeostasis,lake littoral, macroinvertebrates, mismatch, nutrient ratios, phosphorus.

Nitrogen isotope ratios in estuarine biota collected along a nutrient gradient in Narragansett Bay, Rhode Island, USA

Stable nitrogen isotope ratios were used to study the incorporation of anthropogenically-derived nitrogen into the food webs of salt marsh systems along a contamination gradient in Narragansett Bay. Nitrogen isotope ratios ( δ 15N) were measured in six estuarine species collected from three marshes along this gradient, monthly from June to October between 1997 and 1999. A significant decrease in δ 15N was found with distance along the estuary for four of the six species. Significant differences were found among monthly isotope ratios for some species. Nitrogen isotope ratios in sea lettuce ( Ulva lactuca) increased during the summer season with highest δ 15N values measured during September and October. This trend was most pronounced at the station receiving the highest nutrient inputs. Elevated δ 15N values at this station appeared to correlate with seawater ammonia/nitrate concentration ratios. The temporal variations in δ 15N suggest that care should be taken in species selection and the design of sampling schemes of studies using δ 15N for monitoring anthropogenic nutrients in aquatic systems. Sampling programs designed to determine long-term trends should consider species that do not show rapid fluctuations in isotope ratios. The mud snail, Nassarius obsoletus, responded this way in the present study. Studies designed to measure short-term changes should include species such as U. lactuca, which rapidly respond to isotope changes. The results from this study also help to establish a baseline for nitrogen isotope values in Narragansett Bay. This information can be used to monitor future trends in nitrogen inputs to this estuary.

Reproduction and seasonal occurrence of the copper shark, Carcharhinus brachyurus, from north Patagonia, Argentina

Abstract The copper shark, Carcharhinus brachyurus, is the only member of its genus with a preferred habitat in temperate waters, and it usually gives birth in the cooler extremes of its range. Maturation patterns, reproductive condition, monthly sex ratios, and seasonal occurrence of copper sharks were analysed, mostly from Anegada Bay (Argentina), a presumed nursery area for the species. Males mature between 200 and 220 cm total length (LT), with a 50% size at maturity (L50) of 216.18 cm LT. Females mature between 215 and 223 cm LT (with an L50 of 222.16 cm LT). Maturity off Argentina is at a slightly smaller size than off South Africa and Australia. There is no sexual dimorphism in size at maturity. Only two pregnant females, each carrying 16 advanced embryos, were caught. The hepatosomatic index (IH) of adult males showed significant monthly changes, related possibly to an increase in the gonadosomatic index (IG). IH and IG of adult females showed no significant trend throughout the fishing season. The IH of adult females was significantly correlated with maximum diameter of ovarian follicles. Small translucent ovarian follicles in two gravid females indicated that ovarian and gestation cycles run sequentially, with maturation of oocytes subsequent to parturition. Neither newborns nor significant numbers of females bearing term embryos were recorded, and there was no evidence of a copper shark primary nursery area in Anegada Bay. However, most copper sharks in Anegada Bay were large juveniles and sub-adults. The species is found off Argentina from October to late March, but they do not move southwards to Anegada Bay until December, and they leave the bay again by April. These movements appear to be related more to water temperature rather than to migration of potential prey. Monthly variation in sex ratios is associated mainly with fluctuations in the sex ratios of juveniles.

An Interpretation of Energy Dependence of Delayed Neutron Yields in the Resonance Region for 235U and 239Pu

Possible fluctuation in the delayed neutron yields (DNYs) in the resonance region was predicted on the basis of experimental data of mass distribution of fission fragments at resonances. Analyzed according to the multimodal random neck rupture model of fission, the small variations in the experimental mass distribution were attributed to fluctuations in the branching ratios to different modes of fission. Using the results of analysis of measured data for 235U and 239Pu, the DNYs were calculated for each resonance by the summation method, considering 271 precursors and evaluated data of delayed neutron emission probability. It was found that the DNYs should have local dips for 235U and spikes for 239Pu at resonances.

Chiral phase transition in dissipative dynamics

Numerical simulations of the chiral phase transition in the (3+1)-dimensional $O(4)$ model are presented. The evolutions of the chiral field follow purely dissipative dynamics, starting from random chirally symmetric initial configurations down to the true vacuum with spontaneously broken symmetry. The model stabilizes topological textures which are formed together with domains of a disoriented chiral condensate (DCC) during the roll-down phase. The classically evolving field acts as a source for the emission of pions and $\ensuremath{\sigma}$ mesons. The exponents of power laws for the growth of angular correlations and for emission rates are extracted. Fluctuations in the abundance ratios for neutral and charged pions are compared with those for uncorrelated sources as a potential signature for the chiral phase transition after heavy-ion collisions. It is found that the presence of stabilizing textures (baryons and antibaryons) prevents the sufficiently rapid growth of the DCC domain size, so observability of anomalous tails in the abundance ratios is unlikely. However, the transient formation of growing DCC domains causes sizable broadening of the distributions as compared to the statistical widths of generic sources.

COMPARATIVE STUDY OF BENTHIC AND PELAGIC POPULATIONS OF BODOTRIA SIMILIS (CUMACEA) FROM IZU PENINSULA, SOUTHERN JAPAN

Abstract A comparative survey of both benthic and pelagic populations of the cumacean Bodotria similis was conducted in Oura Bay, Izu Peninsula, Japan. In the benthic populations, Bodotria similis, Bodotria pulex, Cumella spp., and Dimorphostylis spp. were dominant, and B. similis and B. pulex were spatially segregated throughout the year. The density of B. similis in the benthic population was low in summer and autumn, increased during winter, and was highest in early spring. Seasonal fluctuations in size classes and sex ratios within the benthic population were minimal, and ovigerous females and manca larvae occurred throughout the year. Size-frequency histograms of the benthic population suggest the presence of six developmental stages for each sex and that females produce more than one brood in their lifetime. Nighttime patterns of occurrence of planktonic Bodotria similis varied seasonally but peaked just after the sunset in spring and winter. The swimming individuals consisted of males and young, bu...