49 research outputs found
Polyandry and Polygyny in a Social Rodent: An Integrative Perspective Based on Social Organization, Copulations, and Genetics
Animal mating systems have fascinated biologists for thousands of years. Ways to describe a mating system include determining social organization, observing copulations, or using genetics to assign parentage. Social organization can be difficult to quantify, however, documentation of copulations is often challenging, many copulations do not produce offspring, and genetic variation is sometimes minimal. Here we use data from a 7-year study of wild white-tailed prairie dogs (WTPDs, Cynomys leucurus) living in Colorado USA to estimate the frequencies of polyandry (i.e., copulation with ≥2 males) and polygyny (i.e., copulation with ≥2 females) from three independent approaches: (1) determination of the number of males and females living in the same territory (social organization); (2) observations of copulations; and (3) genetic assignments of paternity from seven polymorphic microsatellites. We predicted that our three approaches would yield similar estimates of polyandry and polygyny. Because a WTPD female's period of sexual receptivity each spring is limited to several hours on a single day, we also predicted that frequencies of polyandry and polygyny would be lower for WTPDs than for animals with longer periods of receptivity. Our results did not support these predictions. For polyandry, observations of copulations and genetics indicated similar overall percentages (27%), but social organization indicated a much lower percentage (3%). For polygyny, observations of copulations indicated the highest overall percentage (84%), then social organization (59%), then genetics (46%). All three approaches showed striking annual variation in the frequencies of WTPD polyandry and polygyny. Long-term studies that integrate behavioral and genetic insights can provide a detailed view of a mating system, but feasibility will depend on ease of capture, visibility of copulations, length of mating season, research objectives, and genetic variation
Real-time imputation of missing predictor values in clinical practice
Use of prediction models is widely recommended by clinical guidelines, but
usually requires complete information on all predictors that is not always
available in daily practice. We describe two methods for real-time handling of
missing predictor values when using prediction models in practice. We compare
the widely used method of mean imputation (M-imp) to a method that personalizes
the imputations by taking advantage of the observed patient characteristics.
These characteristics may include both prediction model variables and other
characteristics (auxiliary variables). The method was implemented using
imputation from a joint multivariate normal model of the patient
characteristics (joint modeling imputation; JMI). Data from two different
cardiovascular cohorts with cardiovascular predictors and outcome were used to
evaluate the real-time imputation methods. We quantified the prediction model's
overall performance (mean squared error (MSE) of linear predictor),
discrimination (c-index), calibration (intercept and slope) and net benefit
(decision curve analysis). When compared with mean imputation, JMI
substantially improved the MSE (0.10 vs. 0.13), c-index (0.70 vs 0.68) and
calibration (calibration-in-the-large: 0.04 vs. 0.06; calibration slope: 1.01
vs. 0.92), especially when incorporating auxiliary variables. When the
imputation method was based on an external cohort, calibration deteriorated,
but discrimination remained similar. We recommend JMI with auxiliary variables
for real-time imputation of missing values, and to update imputation models
when implementing them in new settings or (sub)populations.Comment: 17 pages, 6 figures, to be published in European Heart Journal -
Digital Health, accepted for MEMTAB 2020 conferenc
Pion Mass Effects in the Large Limit of \chiPT
We compute the large effective action of the non-linear
sigma model including the effect of the pion mass to order
. This action is more complex than the one corresponding
to the chiral limit not only because of the pion propagators but also because
chiral symmetry produce new interactions proportional to .
We renormalize the action by including the appropriate counter terms and find
the renormalization group equations for the corresponding couplings. Then we
estudy the unitarity propierties of the scattering amplitudes. Finally our
results are applied to the particular case of the linear sigma model and also
are used to fit the pion scattering phase shifts.Comment: FT/UCM/18/9
The patient perspective on absence of disease activity in rheumatoid arthritis: A survey to identify key domains of patient-perceived remission
© 2017, BMJ Publishing Group. All rights reserved. Background: Guidelines suggest treatment in rheumatoid arthritis (RA) to target remission, in close consultation with the patient. Our recent qualitative study of the patients' perspective on remission in RA identified 26 domains. The current study aimed to identify a short list of the most important aspects to inform future research. Methods: Patients with RA from the Netherlands, the UK, Austria, Denmark, France and the USA completed a survey that contained all domains identified in our qualitative study. They rated domains for importance ('not important', 'important' or 'essential' to characterise a period of remission) and if important or essential, whether this domain needs to be 'less', 'almost gone' or 'gone' to reflect remission. Respondents were also asked to determine their personal top 3 most important/ essential domains. Frequency of specific domains in the top 3 was calculated, and domains were sorted on the percentage of patients that evaluated a particular domain as 'essential'. Results: Of 274 respondents, 75% were female, mean (SD) age 57(13) years, disease duration 12(9) years. The top 3 were as follows: pain (67%), fatigue (33%) and independence (19%); domains most frequently rated as 'essential' were as follows: pain (60%), being mobile (52%), physical function (51%), being independent (47%) and fatigue (41%). Pain needed to be less (13%), almost gone (42%) or gone (45%) to reflect remission. Similar patterns were seen for fatigue, independence, mobility and physical functioning. Conclusion: Patients identified pain, fatigue and independence as the most important domains of RA disease activity that need to be improved to reflect remission
The Structural Biology Knowledgebase: a portal to protein structures, sequences, functions, and methods
The Protein Structure Initiative’s Structural Biology Knowledgebase (SBKB, URL: http://sbkb.org) is an open web resource designed to turn the products of the structural genomics and structural biology efforts into knowledge that can be used by the biological community to understand living systems and disease. Here we will present examples on how to use the SBKB to enable biological research. For example, a protein sequence or Protein Data Bank (PDB) structure ID search will provide a list of related protein structures in the PDB, associated biological descriptions (annotations), homology models, structural genomics protein target status, experimental protocols, and the ability to order available DNA clones from the PSI:Biology-Materials Repository. A text search will find publication and technology reports resulting from the PSI’s high-throughput research efforts. Web tools that aid in research, including a system that accepts protein structure requests from the community, will also be described. Created in collaboration with the Nature Publishing Group, the Structural Biology Knowledgebase monthly update also provides a research library, editorials about new research advances, news, and an events calendar to present a broader view of structural genomics and structural biology
The effect of colony size on individual alertness of prairie dogs (Sciuridae: Cynomys spp.)
From 1974 to 1976, I examined individual alertness of two species of squirrels (Sciuridae): loosely colonial white-tailed prairie dogs (Cynomys leucurus) and densely colonial black-tailed prairie dogs (C. ludovicianus). By observing single adults for 30-min periods and recording various measures of alertness, I investigated the effects on individual alertness of four variables, all of which are directly related to ward (subcolony) size and ward density. Conclusions were based on data from 188 white-tail observations and 280 black-tail observations. Individual alertness consistently correlated negatively with effective increases in ward size and ward density. I discuss various hypotheses that might explain these negative correlations, and conclude that decreased individual alertness is an important benefit of prairie dog coloniality.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23576/1/0000537.pd
Why do female prairie dogs copulate with more than one male?—Insights from long-term research
Data from: Prairie dogs increase fitness by killing interspecific competitors
Interspecific competition commonly selects for divergence in ecology, morphology, or physiology, but direct observation of interspecific competition under natural conditions is difficult. Herbivorous white-tailed prairie dogs (Cynomys leucurus) employ an unusual strategy to reduce interspecific competition: they kill, but do not consume, herbivorous Wyoming ground squirrels (Urocitellus elegans) encountered in the prairie dog territories. Results from a 6-year study in Colorado USA revealed that interspecific killing (IK) of ground squirrels by prairie dogs was common, involving 47 different killers; 19 prairie dogs were serial killers in the same or consecutive years, and 30% of female prairie dogs killed at least one ground squirrel over their lifetimes. Females that killed ground squirrels had significantly higher annual and lifetime fitness than nonkillers, probably because of decreased interspecific competition for vegetation. Our results document the first case of IK among herbivorous mammals in the wild, and show that IK enhances fitness for animals living under natural conditions
Demography and Population Dynamics of Prairie Dogs
For the last 14 years, we have been studying the sociobiology, demography, and population dynamics of blacktailed prairie dogs (Cynomys ludovicianus) in Wind Cave National Park, South Dakota. Our study colony covers 6.6 hectares (16 acres) and has not expanded during the period of research; in late spring of each year the colony contains a mean ± SD of 133 ± 29 adults and yearlings and 81 ± 33 juveniles. We have discovered four surprising aspects of the demography and populations dynamics of prairie dogs. (1) Mortality during the first year is approximately 50% for both sexes. Those males that survive the first year can live as long as 5 years, and females that survive the first year can live as long as 7 years. (2) Litter size ranges from 1 to 6, the mean ± SD is 3.05 ± 1.08, and the mode is 3. (3) Although individuals of both sexes usually defer first breeding until the second year, 9% of females and 3% of males first produce offspring as yearlings. (4) Infanticide is the major source of juvenile mortality, accounting for the partial or total demise of 51% of all litters born. In the most common type of infanticide, lactating females kill the unweaned offspring of their sisters and daughters