A kill curve for Phanerozoic marine species

Paleobiology ◽  
1991 ◽  
Vol 17 (1) ◽  
pp. 37-48 ◽  
Author(s):  
David M. Raup
Keyword(s):  
Fossil Record ◽  
Marine Species ◽  
Low Risk ◽  
Extinction Rate ◽  
Time Intervals ◽  
Typical Species ◽  
Risk Of Extinction ◽  
The Mean ◽  
Stratigraphic Ranges ◽  
Kill Curve

A kill curve for Phanerozoic species is developed from an analysis of the stratigraphic ranges of 17,621 genera, as compiled by Sepkoski. The kill curve shows that a typical species' risk of extinction varies greatly, with most time intervals being characterized by very low risk. The mean extinction rate of 0.25/m.y. is thus a mixture of long periods of negligible extinction and occasional pulses of much higher rate. Because the kill curve is merely a description of the fossil record, it does not speak directly to the causes of extinction. The kill curve may be useful, however, to limit choices of extinction mechanisms.

Fossil preservation and the stratigraphic ranges of taxa

Paleobiology ◽  
1996 ◽  
Vol 22 (2) ◽  
pp. 121-140 ◽  
Author(s):  
Mike Foote ◽  
David M. Raup
Keyword(s):  
Fossil Record ◽  
Mammalian Species ◽  
Evolutionary Rates ◽  
Extinction Rate ◽  
Mammal Species ◽  
Original Distribution ◽  
Lower Ordovician ◽  
Stratigraphic Ranges ◽  
Fossil Preservation ◽  
Rule Out

The incompleteness of the fossil record hinders the inference of evolutionary rates and patterns. Here, we derive relationships among true taxonomic durations, preservation probability, and observed taxonomic ranges. We use these relationships to estimate original distributions of taxonomic durations, preservation probability, and completeness (proportion of taxa preserved), given only the observed ranges. No data on occurrences within the ranges of taxa are required. When preservation is random and the original distribution of durations is exponential, the inference of durations, preservability, and completeness is exact. However, reasonable approximations are possible given non-exponential duration distributions and temporal and taxonomic variation in preservability. Thus, the approaches we describe have great potential in studies of taphonomy, evolutionary rates and patterns, and genealogy.Analyses of Upper Cambrian-Lower Ordovician trilobite species, Paleozoic crinoid genera, Jurassic bivalve species, and Cenozoic mammal species yield the following results: (1) The preservation probability inferred from stratigraphic ranges alone agrees with that inferred from the analysis of stratigraphic gaps when data on the latter are available. (2) Whereas median durations based on simple tabulations of observed ranges are biased by stratigraphic resolution, our estimates of median duration, extinction rate, and completeness are not biased. (3) The shorter geologic ranges of mammalian species relative to those of bivalves cannot be attributed to a difference in preservation potential. However, we cannot rule out the contribution of taxonomic practice to this difference. (4) In the groups studied, completeness (proportion of species [trilobites, bivalves, mammals] or genera [crinoids] preserved) ranges from 60% to 90%. The higher estimates of completeness at smaller geographic scales support previous suggestions that the incompleteness of the fossil record reflects loss of fossiliferous rock more than failure of species to enter the fossil record in the first place.

Diversity and evolutionary rates of Cambro-Ordovician nautiloids

Paleobiology ◽  
1981 ◽  
Vol 7 (2) ◽  
pp. 216-229 ◽  
Author(s):  
Rex E. Crick
Keyword(s):  
North American ◽  
Fossil Record ◽  
Evolutionary Rates ◽  
Time Interval ◽  
Time Intervals ◽  
Frequency Distributions ◽  
Extinction Rates ◽  
History Of ◽  
Biological Aspects ◽  
Stratigraphic Ranges

The history of diversity, origination and extinction of Cambro-Ordovician nautiloid cephalopods is explored to determine if differences in evolutionary rates between nautiloid orders are sufficient to document significantly high or low rates of evolutionary turnover (taxotely of Raup and Marshall 1980). The stratigraphic ranges of 425 nautiloid genera are analyzed for this purpose.Evolutionary rates for five of the seven time intervals analyzed fall within frequency distributions of rates which are thought to be characteristic for a given time interval (horotelic distribution of Simpson 1944). Sufficient heterogeneity is present among extinction rates of Arenigian orders and origination rates of Caradocian orders to reject the null hypotheses of horotely in favor of taxotely. The orders Ellesmerocerida and Tarphycerida, each with a significantly high rate of extinction (P ≥ 0.99), and the Actinocerida, with a significantly low rate of extinction (P ≥ 0.99), were responsible for taxotely during the Arenigian. The Oncocerida and Discosorida, each with a significantly high rate of origination (P ≥ 0.99), were responsible for taxotely during the Caradocian. In each case, taxotely is attributable to the influence of North American endemics. This effect is believed to be more the result of real biological aspects of nautiloid evolution than an artifact of the fossil record.

Gaps in the fossil record

Paleobiology ◽  
1985 ◽  
Vol 11 (2) ◽  
pp. 221-226 ◽  
Author(s):  
Eric W. Holman
Keyword(s):  
Random Sampling ◽  
Fossil Record ◽  
Statistical Properties ◽  
Extinction Rate ◽  
Higher Taxa ◽  
Stratigraphic Ranges

Gaps in the fossil record can be identified in compilations of stratigraphic ranges of lower taxa classified within higher taxa. Statistical properties of such gaps suggest the following conclusions. First, the random sampling model most commonly used to correct for incompleteness in the record is inconsistent with the data. Second, the decline in taxonomic extinction rate during the Phanerozoic is not just an artifact of an increase in the completeness of the record.

The relation between second-trimester placental elasticity and poor obstetric outcomes in low-risk pregnancies

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Murat Akbas ◽  
Faik Mumtaz Koyuncu ◽  
Burcu Artunç-Ülkümen ◽  
Gökce Akbas
Keyword(s):  
Birth Weight ◽  
Pregnant Women ◽  
Value Added ◽  
Shear Wave Elastography ◽  
Multiple Regression Model ◽  
Low Risk ◽  
Obstetric Outcomes ◽  
Second Trimester ◽  
The Mean ◽  
Random Measurements

AbstractObjectivesIncreased placental stiffness is associated with various pathological conditions. Our objective was to evaluate the relation between the second-trimester placental elasticity value in low-risk pregnant women and poor obstetric outcomes.MethodsA total of 143 pregnant women were enrolled. Placental elasticity values were measured using the transabdominal point shear wave elastography method. 10 random measurements were obtained from different areas of the placenta. The mean was accepted as the mean placental elasticity value. Logistic regression analyses were performed to identify independent variables associated with obstetric outcomes.ResultsSecond-trimester placental elasticity value was significantly and positively associated with the poor obstetric outcomes (p=0.038). We could predict a poor outcome with 69.2% sensitivity and 60.7% specificity if we defined the placental elasticity cut-off as 3.19 kPa. Furthermore, in the multiple regression model, the placental elasticity value added significantly to the prediction of birth weight (p=0.043).ConclusionsOur results showed that the pregnancies with a stiffer placenta in the second trimester were associated with an increased likelihood of exhibiting poor obstetric outcomes. Also, placental elasticity was independently associated with birth weight.

scholarly journals Repeated Pelvic Radiographs in Infants, After Harness Treatment for Developmental Dysplasia of the Hip, Carry Very Low Radiation Risk

2021 ◽  
Author(s):  
Elizabeth Vogel ◽  
Thomas Leaver ◽  
Fiona Wall ◽  
Ben Johnson ◽  
Michael Uglow ◽  
...  
Keyword(s):  
Radiation Exposure ◽  
Radiation Risk ◽  
Low Risk ◽  
Lifetime Risk ◽  
Body Region ◽  
Pavlik Harness ◽  
Pelvic Radiographs ◽  
Risk Of Malignancy ◽  
The Mean

Abstract Objective There are no data on the effect of X-Ray irradiation to the vulnerable pelvic organs of babies during DDH follow-up. This study aims to calculate, for the first time, the radiation exposure to infants during follow-up for DDH harness treatment, and thus quantify the lifetime risk of malignancy. Methods Patients who had completed 5 years’ follow-up following successful Pavlik harness treatment were identified from the hospital DDH database. The radiation dose was extracted from the Computerised Radiology Information System database for every radiograph of every patient. The effective dose (ED) was calculated using conversion coefficients for age, sex and body region irradiated. Cumulative ED was compared to Health Protection Agency standards to calculate lifetime risk of malignancy from the radiographs. Results All radiographs of 40 infants, successfully treated in Pavlik harness for DDH, were assessed. The mean number of AP pelvis radiographs was 7.00 (range: 6–9, mode: 7). The mean cumulative ED was 0.25 mSv (Range: 0.11–0.46, SD: 0.07). This is far lower than the annual ‘safe’ limit for healthcare workers of 20 mSv and is categorised as “Very Low Risk”. Conclusion Clinicians involved in the treatment DDH can be re-assured that the cumulative radiation exposure from pelvic radiographs following Pavlik harness treatment is “Very Low Risk”. Whilst being mindful of any radiation exposure in children, this study provides a scientific answer that help addresses parental concerns.

scholarly journals Non-Lynch Familial and Early-Onset Colorectal Cancer Explained by Accumulation of Low-Risk Genetic Variants

Cancers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 3857
Author(s):  
Pilar Mur ◽  
Nuria Bonifaci ◽  
Anna Díez-Villanueva ◽  
Elisabet Munté ◽  
Maria Henar Alonso ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Risk Score ◽  
Early Onset ◽  
Low Risk ◽  
Polygenic Risk Score ◽  
Polygenic Risk ◽  
Pathogenic Variants ◽  
Predisposing Genes ◽  
The Mean ◽  
Early Onset Colorectal Cancer

A large proportion of familial and/or early-onset cancer patients do not carry pathogenic variants in known cancer predisposing genes. We aimed to assess the contribution of previously validated low-risk colorectal cancer (CRC) alleles to familial/early-onset CRC (fCRC) and to serrated polyposis. We estimated the association of CRC with a 92-variant-based weighted polygenic risk score (wPRS) using 417 fCRC patients, 80 serrated polyposis patients, 1077 hospital-based incident CRC patients, and 1642 controls. The mean wPRS was significantly higher in fCRC than in controls or sporadic CRC patients. fCRC patients in the highest (20th) wPRS quantile were at four-fold greater CRC risk than those in the middle quantile (10th). Compared to low-wPRS fCRC, a higher number of high-wPRS fCRC patients had developed multiple primary CRCs, had CRC family history, and were diagnosed at age ≥50. No association with wPRS was observed for serrated polyposis. In conclusion, a relevant proportion of mismatch repair (MMR)-proficient fCRC cases might be explained by the accumulation of low-risk CRC alleles. Validation in independent cohorts and development of predictive models that include polygenic risk score (PRS) data and other CRC predisposing factors will determine the implementation of PRS into genetic testing and counselling in familial and early-onset CRC.

The Evolutionary Diversity and Ecological Complexity of Coral Reefs

2011 ◽  
Vol 17 ◽  
pp. 111-120 ◽  
Author(s):  
Nancy Knowlton ◽  
Jeremy Jackson
Keyword(s):  
Coral Reefs ◽  
Small Proportion ◽  
Fossil Record ◽  
Marine Species ◽  
Foreseeable Future ◽  
Ecological Complexity ◽  
The Face ◽  
Open Question ◽  
Trophic Linkages ◽  
Bounce Back

Coral reefs are the most biodiverse marine ecosystems on the planet, with at least one quarter of all marine species associated with reefs today. This diversity, which remains very poorly understood, is nevertheless extraordinary when one considers the small proportion of ocean area that is occupied by coral reefs. Networks of competitive and trophic linkages are also exceptionally complex and dense. Reefs have a long fossil record, although extensive reef building comes and goes. In the present, coral reefs sometimes respond dramatically to disturbances, and collapses are not always followed by recoveries. Today, much of this failure to recover appears to stem from the fact that most reefs are chronically stressed by human activities, judging by observations of recovery at exceptional locations where local human activity is minimal. How long reefs can continue to bounce back in the face of warming and acidification remains an open question. Another big uncertainty is how much loss of biodiversity will occur with the inevitable degradation of coral reefs that will continue in most places for the foreseeable future.

scholarly journals Comparison of Bite Force in Patients After Treatment of Mandibular Fractures With 3-Dimensional Locking Miniplate and Standard Miniplates

2019 ◽  
Vol 1 (1) ◽  
pp. 7-10
Author(s):  
Gaurav Singh ◽  
Madan Mishra ◽  
Amit Gaur ◽  
Dhritiman Pathak
Keyword(s):  
Treatment Strategies ◽  
Bite Force ◽  
Mandibular Fractures ◽  
Time Intervals ◽  
Experimental Conditions ◽  
3 Dimensional ◽  
The Mean ◽  
Group 2 ◽  
Drilling Conditions ◽  
Group 1

Background: Fractures of the mandible can be studied and described in anatomic terms, functional considerations, treatment strategies, and outcome measures. The performance of any fixation system depends on multiple factors including plate adaptation, screw placement, bone quality, drilling conditions, and postoperative patient compliance. Bite force assesses masticatory muscle function under clinical and experimental conditions. Method: 30 patients with isolated, noncomminuted mandibular fractures were randomly divided into two equal groups. Group 1 patients were treated using 3-dimensional locking miniplates and group 2 patients were treated with standard miniplates. The bite forces were recorded at definite time intervals: preoperatively, and second week, sixth week, third month, and sixth month postoperatively. Result: At 6 weeks postoperative, 3 month postoperative, and 6 month postoperative, the mean bite force was found to be significantly higher among group 1 patients as compared to those in group 2 in all the sites. While at 2 week postoperative, the mean bite force was found to be significantly higher in Group 2 as compared to Group 1 at incisor region. Conclusion: The overall results of the present study show better performance in bite force for the 3-dimensional locking miniplate when compared with standard miniplates.

scholarly journals Sernbo score predicts survival after intracapsular hip fracture in the elderly

2013 ◽  
Vol 95 (1) ◽  
pp. 29-33 ◽  
Author(s):  
EJC Dawe ◽  
E Lindisfarne ◽  
T Singh ◽  
I McFadyen ◽  
P Stott
Keyword(s):  
Hip Fracture ◽  
High Risk ◽  
Risk Group ◽  
Characteristic Curve ◽  
Social Situation ◽  
High Risk Group ◽  
Low Risk ◽  
Risk Of Death ◽  
Intracapsular Hip Fracture ◽  
The Mean

Introduction The Sernbo score uses four factors (age, social situation, mobility and mental state) to divide patients into a high-risk and a low-risk group. This study sought to assess the use of the Sernbo score in predicting mortality after an intracapsular hip fracture. Methods A total of 259 patients with displaced intracapsular hip fractures were included in the study. Data from prospectively generated databases provided 22 descriptive variables for each patient. These included operative management, blood tests and co-mobidities. Multivariate analysis was used to identify significant predictors of mortality. Results The mean patient age was 85 years and the mean follow-up duration was 1.5 years. The one-year survival rate was 92% (±0.03) in the low-risk group and 65% (±0.046) in the high-risk group. Four variables predicted mortality: Sernbo score >15 (p=0.0023), blood creatinine (p=0.0026), ASA (American Society of Anaesthesiologists) grade >3 (p=0.0038) and non-operative treatment (p=0.0377). Receiver operating characteristic curve analysis showed the Sernbo score as the only predictor of 30-day mortality (area under curve 0.71 [0.65–0.76]). The score had a sensitivity of 92% and a specificity of 51% for prediction of death at 30 days. Conclusions The Sernbo score identifies patients at high risk of death in the 30 days following injury. This very simple score could be used to direct extra early multidisciplinary input to high-risk patients on admission with an intracapsular hip fracture.

Annual hazard rates of recurrence for breast cancer after primary therapy.

1996 ◽  
Vol 14 (10) ◽  
pp. 2738-2746 ◽  
Author(s):  
T Saphner ◽  
D C Tormey ◽  
R Gray
Keyword(s):  
Breast Cancer ◽  
Eastern Cooperative Oncology Group ◽  
Entire Group ◽  
Hazard Rates ◽  
Primary Therapy ◽  
Time Intervals ◽  
Differentiating Agents ◽  
The Mean ◽  
Lower Hazard

PURPOSE To determine if the long-term increase of recurrence for breast cancer is stable or slowly decreasing, or if it ever reaches zero; and to determine the effect of prognostic factors on the hazard of recurrence. METHODS All patients entered onto the seven completed and unblinded Eastern Cooperative Oncology Group (ECOG) coordinated studies of postoperative adjuvant therapy for breast cancer were analyzed in terms of annual hazard of recurrence of breast cancer. RESULTS For the entire group, the peak hazard of recurrence occurred in the interval of 1 to 2 years. The hazard decreased consistently in the interval of 2 to 5 years. Beyond 5 years, the hazard of recurrence decreased very, very slowly through year 12. The average hazard of recurrence between years 5 and 12 for the entire population was 4.3% per year. The pattern of a peak hazard of recurrence during the first 5 years with a slowly decreasing hazard of recurrence beyond 5 years was also observed to varying degrees in most subsets. Higher risk subsets such as patients with more than three nodes positive had a higher hazard of recurrence at all time intervals, while lower risk subsets such as patients with negative nodes had a lower hazard of recurrence in all time periods. CONCLUSION Patients 5 years postsurgery for breast cancer appear to have a very slowly decreasing hazard of recurrence. The mean hazard of recurrence between years 5 to 12 postsurgery is 4.3% per year. This group of patients may be well suited for trials evaluating cytostatic drugs or differentiating agents.

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