scholarly journals Sperm morphology and sperm velocity in passerine birds

2008 ◽  
Vol 276 (1659) ◽  
pp. 1175-1181 ◽  
Author(s):  
Stefan Lüpold ◽  
Sara Calhim ◽  
Simone Immler ◽  
Tim R Birkhead
Keyword(s):  
Sperm Morphology ◽  
Empirical Studies ◽  
Theoretical Models ◽  
Study Groups ◽  
Passerine Birds ◽  
Single Family ◽  
Sperm Velocity ◽  
Evolutionary Forces ◽  
Wide Range ◽  
Main Determinants

Sperm velocity is one of the main determinants of the outcome of sperm competition. Since sperm vary considerably in their morphology between and within species, it seems likely that sperm morphology is associated with sperm velocity. Theory predicts that sperm velocity may be increased by enlarged midpiece (energetic component) or flagellum length (kinetic component), or by particular ratios between sperm components, such as between flagellum length and head size. However, such associations have rarely been found in empirical studies. In a comparative framework in passerine birds, we tested these theoretical predictions both across a wide range of species and within a single family, the New World blackbirds (Icteridae). In both study groups, sperm velocity was influenced by sperm morphology in the predicted direction. Consistent with theoretical models, these results show that selection on sperm morphology and velocity are likely to be concomitant evolutionary forces.

scholarly journals Correlated pay-offs are key to cooperation

2016 ◽  
Vol 371 (1687) ◽  
pp. 20150084 ◽  
Author(s):  
Michael Taborsky ◽  
Joachim G. Frommen ◽  
Christina Riehl
Keyword(s):  
Kin Selection ◽  
Empirical Studies ◽  
Decision Rules ◽  
Theoretical Models ◽  
Future Research ◽  
Confounding Effect ◽  
Evolutionary Mechanisms ◽  
General Belief ◽  
Wide Range ◽  
Cooperatively Breeding

The general belief that cooperation and altruism in social groups result primarily from kin selection has recently been challenged, not least because results from cooperatively breeding insects and vertebrates have shown that groups may be composed mainly of non-relatives. This allows testing predictions of reciprocity theory without the confounding effect of relatedness. Here, we review complementary and alternative evolutionary mechanisms to kin selection theory and provide empirical examples of cooperative behaviour among unrelated individuals in a wide range of taxa. In particular, we focus on the different forms of reciprocity and on their underlying decision rules, asking about evolutionary stability, the conditions selecting for reciprocity and the factors constraining reciprocal cooperation. We find that neither the cognitive requirements of reciprocal cooperation nor the often sequential nature of interactions are insuperable stumbling blocks for the evolution of reciprocity. We argue that simple decision rules such as ‘help anyone if helped by someone’ should get more attention in future research, because empirical studies show that animals apply such rules, and theoretical models find that they can create stable levels of cooperation under a wide range of conditions. Owing to its simplicity, behaviour based on such a heuristic may in fact be ubiquitous. Finally, we argue that the evolution of exchange and trading of service and commodities among social partners needs greater scientific focus.

Paradoxes of reservation wage setting in the Russian labor market. Part I

2016 ◽  
pp. 5-27
Author(s):  
R. Kapeliushnikov ◽  
A. Lukyanova
Keyword(s):  
Labor Market ◽  
Empirical Studies ◽  
Reservation Wage ◽  
Wage Setting ◽  
Reservation Wages ◽  
Monitoring Survey ◽  
Main Determinants ◽  
Subjective Estimates ◽  
Objective Indicators

Using panel data from the Russian Longitudinal Monitoring Survey for 2006-2014, the paper investigates reservation wages setting in the Russian labor market. The sample includes non-employed individuals wishing to get a job (both searchers and non-searchers). The first part of the paper provides a survey of previous empirical studies, describes data and analyzes subjective estimates of reservation wages in comparison with various objective indicators of actual wages. The analysis shows that wage aspirations of the majority of Russian non-employed individuals are overstated. However their wage expectations are rather flexible and decrease rapidly as the search continues that prevents high long-term unemployment. The second part of the paper provides an econometric analysis of main determinants of reservation wage and its impact on probability of re-employment and wages on searchers’ new jobs.

Studying Populations of Online Communities

2019 ◽  
pp. 173-193
Author(s):  
Benjamin Mako Hill ◽  
Aaron Shaw
Keyword(s):  
Online Communities ◽  
Information Diffusion ◽  
Diffusion Processes ◽  
Empirical Studies ◽  
Population Level ◽  
Study Groups ◽  
Population Based ◽  
Large Majority ◽  
Community Processes ◽  
Published Research

While the large majority of published research on online communities consists of analyses conducted entirely within individual communities, this chapter argues for a population-based approach, in which researchers study groups of similar communities. For example, although there have been thousands of papers published about Wikipedia, a population-based approach might compare all wikis on a particular topic. Using examples from published empirical studies, the chapter describes five key benefits of this approach. First, it argues that population-level research increases the generalizability of findings. Next, it describes four processes and dynamics that are only possible to study using populations: community-level variables, information diffusion processes across communities, ecological dynamics, and multilevel community processes. The chapter concludes with a discussion of a series of limitations and challenges.

Emerging Syndromes

2017 ◽  
Author(s):  
Kelly C. Allison ◽  
Jennifer D. Lundgren
Keyword(s):  
Empirical Studies ◽  
Theoretical Models ◽  
Future Research ◽  
Night Eating Syndrome ◽  
Statistical Manual ◽  
Night Eating ◽  
Diagnostic And Statistical Manual ◽  
Impairment In Functioning ◽  
Atypical Anorexia Nervosa ◽  
Comorbid Psychopathology

The Diagnostic and Statistical Manual, fifth edition, of the American Psychiatric Association (2013) has designated several disorders under the diagnosis of otherwise specified feeding and eating disorder (OSFED). This chapter evaluates three of these, night eating syndrome (NES), purging disorder (PD), and atypical anorexia nervosa (atypical AN). It also reviews orthorexia nervosa, which has been discussed in the clinical realm as well as the popular press. The history and definition for each is reviewed, relevant theoretical models are presented and compared, and evidence for the usefulness of the models is described. Empirical studies examining the disorders’ independence from other disorders, comorbid psychopathology, and, when available, medical comorbidities, are discussed. Distress and impairment in functioning seem comparable between at least three of these emerging disorders and threshold eating disorders. Finally, remaining questions for future research are summarized.

scholarly journals A developmentally descriptive method for quantifying shape in gastropod shells

2020 ◽  
Vol 17 (163) ◽  
pp. 20190721
Author(s):  
J. Larsson ◽  
A. M. Westram ◽  
S. Bengmark ◽  
T. Lundh ◽  
R. K. Butlin
Keyword(s):  
Empirical Studies ◽  
Three Dimensional ◽  
Shell Shape ◽  
Large Set ◽  
Littorina Saxatilis ◽  
Shape Variation ◽  
Gastropod Shell ◽  
Geometric Morphometric ◽  
Wide Range ◽  
Descriptive Method

The growth of snail shells can be described by simple mathematical rules. Variation in a few parameters can explain much of the diversity of shell shapes seen in nature. However, empirical studies of gastropod shell shape variation typically use geometric morphometric approaches, which do not capture this growth pattern. We have developed a way to infer a set of developmentally descriptive shape parameters based on three-dimensional logarithmic helicospiral growth and using landmarks from two-dimensional shell images as input. We demonstrate the utility of this approach, and compare it to the geometric morphometric approach, using a large set of Littorina saxatilis shells in which locally adapted populations differ in shape. Our method can be modified easily to make it applicable to a wide range of shell forms, which would allow for investigations of the similarities and differences between and within many different species of gastropods.

scholarly journals Personality trait differences across types of entrepreneurs: a systematic literature review

2021 ◽  
Author(s):  
Florentine U. Salmony ◽  
Dominik K. Kanbach
Keyword(s):  
Literature Review ◽  
Personality Traits ◽  
Systematic Literature Review ◽  
Empirical Studies ◽  
Academic Research ◽  
Future Research ◽  
Rural Farmers ◽  
Start Up ◽  
Wide Range ◽  
Research Integration

AbstractThe personality traits that define entrepreneurs have been of significant interest to academic research for several decades. However, previous studies have used vastly different definitions of the term “entrepreneur”, meaning their subjects have ranged from rural farmers to tech-industry start-up founders. Consequently, most research has investigated disparate sub-types of entrepreneurs, which may not allow for inferences to be made regarding the general entrepreneurial population. Despite this, studies have frequently extrapolated results from narrow sub-types to entrepreneurs in general. This variation in entrepreneur samples reduces the comparability of empirical studies and calls into question the reviews that pool results without systematic differentiation between sub-types. The present study offers a novel account by differentiating between the definitions of “entrepreneur” used in studies on entrepreneurs’ personality traits. We conduct a systematic literature review across 95 studies from 1985 to 2020. We uncover three main themes across the previous studies. First, previous research applied a wide range of definitions of the term “entrepreneur”. Second, we identify several inconsistent findings across studies, which may at least partially be due to the use of heterogeneous entrepreneur samples. Third, the few studies that distinguished between various types of entrepreneurs revealed differences between them. Our systematic differentiation between entrepreneur sub-types and our research integration offer a novel perspective that has, to date, been widely neglected in academic research. Future research should use clearly defined entrepreneurial samples and conduct more systematic investigations into the differences between entrepreneur sub-types.

Assessment of needs for care among patients with schizophrenic disorders 15 and 17 years after first onset of psychosis

1997 ◽  
Vol 6 (S1) ◽  
pp. 21-28 ◽  
Author(s):  
Durk Wiersma ◽  
Fokko J. Nienhuis ◽  
Cees J. Slooff ◽  
Robert Giel ◽  
Aant De Jong
Keyword(s):  
Mental Disorders ◽  
Empirical Studies ◽  
Signs And Symptoms ◽  
Expected Improvement ◽  
Chronic Patients ◽  
Cross Sectional ◽  
Wide Range ◽  
Social Disablement ◽  
First Onset

Severe and long term mental disorders, like schizophrenia, show in general a wide range of psychiatric signs and symptoms, psychological and physiological impairments and social disablement (Shepherd, 1994; Wing, 1982) reflecting a variety of mental health needs. Many studies provide only a cross-sectional view of the clinical and social problems of the patient population, for example at intake or admission to a mental hospital. Longitudinal studies following patients after discharge for some period of months or years show in general the expected improvement of functioning (e.g. Nienhuis et al., 1994), but as far as only chronic patients are concerned such a positive change is much less noted. The concept of chronicity of mental disorders would presume that after some time needs are fairly predictable and stable and do not change much over time. Our investigation on the long-term course of schizophrenia (Wiersma et al., 1996; 1997) enables us to study over a period of two years, from 15 to 17 years since first onset of psychosis, the stability or variability of needs in schizophrenic disorder. We are not aware of empirical studies on changes in needs among patients with long-term disorders.

Dynamics and Performance of a Harmonically Excited Vertical Impact Damper

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Sanjiv Ramachandran ◽  
George Lesieutre
Keyword(s):  
Loss Factor ◽  
Vertical Direction ◽  
Theoretical Models ◽  
Coefficient Of Restitution ◽  
Numerical Continuation ◽  
Particle Impact ◽  
Impact Damper ◽  
High Loss ◽  
Wide Range ◽  
And Performance

Particle impact dampers (PIDs) have been shown to be effective in vibration damping. However, our understanding of such dampers is still limited, based on the theoretical models existing today. Predicting the performance of the PID is an important problem, which needs to be investigated more thoroughly. This research seeks to understand the dynamics of a PID as well as those parameters which govern its behavior. The system investigated is a particle impact damper with a ceiling, under the influence of gravity. The base is harmonically excited in the vertical direction. A two-dimensional discrete map is obtained, wherein the variables at one impact uniquely dictate the variables at the next impact. This map is solved using a numerical continuation procedure. Periodic impact motions and “irregular” motions are observed. The effects of various parameters such as the gap clearance, coefficient of restitution, and the base acceleration are analyzed. The dependence of the effective damping loss factor on these parameters is also studied. The loss factor results indicate peak damping for certain combinations of parameters. These combinations of parameters correspond to a region in parameter space where two-impacts-per-cycle motions are observed over a wide range of nondimensional base accelerations. The value of the nondimensional acceleration at which the onset of two-impacts-per-cycle solutions occurs depends on the nondimensional gap clearance and the coefficient of restitution. The range of nondimensional gap clearances over which two-impacts-per-cycle solutions are observed increases as the coefficient of restitution increases. In the regime of two-impacts-per-cycle solutions, the value of nondimensional base acceleration corresponding to onset of these solutions initially decreases and then increases with increasing nondimensional gap clearance. As the two-impacts-per-cycle solutions are associated with high loss factors that are relatively insensitive to changing conditions, they are of great interest to the designer.

Social efficiency of internal affairs bodies

2021 ◽  
Author(s):  
Egor Bunov
Keyword(s):  
Law Enforcement ◽  
Empirical Studies ◽  
Multidimensional Analysis ◽  
Law Enforcement Agencies ◽  
Social Effectiveness ◽  
The Social ◽  
Wide Range ◽  
Degree Of Satisfaction ◽  
Internal Affairs

The monograph contains a theoretical analysis of the social effectiveness of the internal affairs bodies as the degree of satisfaction of the population with the quality of law enforcement activities to protect their interests, rights and freedoms. The results of a multidimensional analysis of empirical studies of the influence of macro - and microsocial factors on the effectiveness of interaction between the population and law enforcement agencies are presented. The article substantiates the criteria for social assessment of the activities of the internal affairs bodies, the use of which allows for practical adjustment of the forms and methods of the management system. For a wide range of readers interested in the practice of applying legal measures of law enforcement.

scholarly journals Kinome Expansion in theFusarium oxysporumSpecies Complex Driven by Accessory Chromosomes

mSphere ◽  
2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Gregory A. DeIulio ◽  
Li Guo ◽  
Yong Zhang ◽  
Jonathan M. Goldberg ◽  
H. Corby Kistler ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Species Complex ◽  
Severe Disease ◽  
Cellular Responses ◽  
Human Pathogens ◽  
Content Type ◽  
Evolutionary Forces ◽  
Environmental Signal ◽  
Wide Range ◽  
Opportunistic Fungal Pathogen

ABSTRACTTheFusarium oxysporumspecies complex (FOSC) is a group of soilborne pathogens causing severe disease in more than 100 plant hosts, while individual strains exhibit strong host specificity. Both chromosome transfer and comparative genomics experiments have demonstrated that lineage-specific (LS) chromosomes contribute to the host-specific pathogenicity. However, little is known about the functional importance of genes encoded in these LS chromosomes. Focusing on signaling transduction, this study compared the kinomes of 12F. oxysporumisolates, including both plant and human pathogens and 1 nonpathogenic biocontrol strain, with 7 additional publicly available ascomycete genomes. Overall,F. oxysporumkinomes are the largest, facilitated in part by the acquisitions of the LS chromosomes. The comparative study identified 99 kinases that are present in almost all examined fungal genomes, forming the core signaling network of ascomycete fungi. Compared to the conserved ascomycete kinome, the expansion of theF. oxysporumkinome occurs in several kinase families such as histidine kinases that are involved in environmental signal sensing and target of rapamycin (TOR) kinase that mediates cellular responses. Comparative kinome analysis suggests a convergent evolution that shapes individualF. oxysporumisolates with an enhanced and unique capacity for environmental perception and associated downstream responses.IMPORTANCEIsolates ofFusarium oxysporumare adapted to survive a wide range of host and nonhost conditions. In addition,F. oxysporumwas recently recognized as the top emerging opportunistic fungal pathogen infecting immunocompromised humans. The sensory and response networks of these fungi undoubtedly play a fundamental role in establishing the adaptability of this group. We have examined the kinomes of 12F. oxysporumisolates and highlighted kinase families that distinguishF. oxysporumfrom other fungi, as well as different isolates from one another. The amplification of kinases involved in environmental signal relay and regulating downstream cellular responses clearly setsFusariumapart from otherAscomycetes. Although the functions of many of these kinases are still unclear, their specific proliferation highlights them as a result of the evolutionary forces that have shaped this species complex and clearly marks them as targets for exploitation in order to combat disease.

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