A seasonal decomposition of the estimated size of a penguin population at Phillip Island, Australia

2005 ◽  
Vol 53 (2) ◽  
pp. 111 ◽  
Author(s):  
H.-C. Yang ◽  
L. E. Chambers ◽  
R. M. Huggins
Keyword(s):  
Population Size ◽  
Sampling Methods ◽  
Seasonal Effects ◽  
Trend Component ◽  
Seasonal Time Series ◽  
The Difference ◽  
Weaker Conditions ◽  
Seasonal Decomposition ◽  
Parametric Estimate ◽  
Non Parametric

Modern non-parametric methods allow the estimation of a population size under weaker conditions than the classical methods if there are frequent capture occasions. Here a non-parametric estimate of the number of penguins occupying Summerland Beach, Phillip Island, Australia, was computed. This estimator did not assume equal catchability of individuals, did not assume a parametric form for the population size as a function of time and allowed individuals to leave and re-enter the population. The resulting estimate was then decomposed into a seasonal component and a trend component using seasonal time series models to facilitate the understanding of the changes in the population size. The estimated seasonal effects quantified the difference between the number of penguins in the breeding and non-breeding season, and the trend component indicated an increase in the population size over the period of the study. The estimates of the number of penguins are shown to be consistent with other estimates obtained from a variety of sampling methods and statistical analyses.

scholarly journals Couplings for determinantal point processes and their reduced Palm distributions with a view to quantifying repulsiveness

2021 ◽  
Vol 58 (2) ◽  
pp. 469-483
Author(s):  
Jesper Møller ◽  
Eliza O’Reilly
Keyword(s):  
Finite Number ◽  
Point Process ◽  
Point Processes ◽  
Parametric Models ◽  
Determinantal Point Processes ◽  
Determinantal Point Process ◽  
The Difference ◽  
Weaker Conditions ◽  
Palm Distributions

AbstractFor a determinantal point process (DPP) X with a kernel K whose spectrum is strictly less than one, André Goldman has established a coupling to its reduced Palm process $X^u$ at a point u with $K(u,u)>0$ so that, almost surely, $X^u$ is obtained by removing a finite number of points from X. We sharpen this result, assuming weaker conditions and establishing that $X^u$ can be obtained by removing at most one point from X, where we specify the distribution of the difference $\xi_u: = X\setminus X^u$. This is used to discuss the degree of repulsiveness in DPPs in terms of $\xi_u$, including Ginibre point processes and other specific parametric models for DPPs.

scholarly journals Large numbers of vertebrates began rapid population decline in the late 19th century

2016 ◽  
Vol 113 (49) ◽  
pp. 14079-14084 ◽  
Author(s):  
Haipeng Li ◽  
Jinggong Xiang-Yu ◽  
Guangyi Dai ◽  
Zhili Gu ◽  
Chen Ming ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Size ◽  
Threatened Species ◽  
Driving Forces ◽  
Population Decline ◽  
Cumulative Effect ◽  
Extinction Time ◽  
Time Period ◽  
Large Numbers ◽  
The Difference

Accelerated losses of biodiversity are a hallmark of the current era. Large declines of population size have been widely observed and currently 22,176 species are threatened by extinction. The time at which a threatened species began rapid population decline (RPD) and the rate of RPD provide important clues about the driving forces of population decline and anticipated extinction time. However, these parameters remain unknown for the vast majority of threatened species. Here we analyzed the genetic diversity data of nuclear and mitochondrial loci of 2,764 vertebrate species and found that the mean genetic diversity is lower in threatened species than in related nonthreatened species. Our coalescence-based modeling suggests that in many threatened species the RPD began ∼123 y ago (a 95% confidence interval of 20–260 y). This estimated date coincides with widespread industrialization and a profound change in global living ecosystems over the past two centuries. On average the population size declined by ∼25% every 10 y in a threatened species, and the population size was reduced to ∼5% of its ancestral size. Moreover, the ancestral size of threatened species was, on average, ∼22% smaller than that of nonthreatened species. Because the time period of RPD is short, the cumulative effect of RPD on genetic diversity is still not strong, so that the smaller ancestral size of threatened species may be the major cause of their reduced genetic diversity; RPD explains 24.1–37.5% of the difference in genetic diversity between threatened and nonthreatened species.

A semi-hybrid model for malaria with limited superinfection

1998 ◽  
Vol 30 (04) ◽  
pp. 1027-1057 ◽  
Author(s):  
Philippe Picard
Keyword(s):  
Stochastic Model ◽  
Population Size ◽  
Hybrid Model ◽  
Human Population ◽  
Threshold Level ◽  
The Other ◽  
The Difference ◽  
The One

Modelling malaria with consistency necessitates the introduction of at least two families of interconnected processes. Even in a Markovian context the simplest fully stochastic model is intractable and is usually transformed into a hybrid model, by supposing that these two families are stochastically independent and linked only through two deterministic connections. A model closer to the fully stochastic model is presented here, where one of the two families is subordinated to the other and just a unique deterministic connection is required. For this model a threshold theorem can be proved but the threshold level is not the one obtained in a hybrid model. The difference disappears only when the human population size approaches infinity.

scholarly journals Measuring SEDs for individual galaxy components

2011 ◽  
Vol 7 (S284) ◽  
pp. 301-305
Author(s):  
Steven P. Bamford ◽  
Boris Häußler ◽  
Alex Rojas ◽  
Marina Vika ◽  
Jim Cresswell
Keyword(s):  
Sampling Methods ◽  
Stellar Populations ◽  
Next Generation ◽  
New Techniques ◽  
Combining Data ◽  
Individual Galaxy ◽  
Non Parametric

AbstractOur project, ‘MegaMorph’, is developing a next-generation tool for decomposing galaxies, in terms of both their structures and stellar populations. By combining data from UV to NIR wavelengths, accounting for morphological peculiarities using non-parametric components, and utilising efficient likelihood sampling methods, we are working to significantly improve the robustness and accuracy of galaxy decomposition. Applying these new techniques to modern large surveys will provide us with a deeper understanding of galaxies.

scholarly journals The Sprotte Needle and Post Dural Puncture Headache following Caesarean Section

1993 ◽  
Vol 21 (3) ◽  
pp. 280-283 ◽  
Author(s):  
A. W. Ross ◽  
C. Greenhalgh ◽  
D. P. McGlade ◽  
I. G. Balson ◽  
S. C. Chester ◽  
...  
Keyword(s):  
Caesarean Section ◽  
Population Size ◽  
Lower Incidence ◽  
Dural Puncture ◽  
Operating Conditions ◽  
Hyperbaric Bupivacaine ◽  
Post Dural Puncture Headache ◽  
The Difference ◽  
Obstetric Population

One hundred and forty-four patients receiving subarachnoid anaesthesia for caesarean section were prospectively analysed for quality of anaesthesia and the occurrence of post dural puncture headache (PDPH). Anaesthesia was administered via 24 gauge Sprotte (n = 104) and 26 gauge Quincke (n = 40) needles using hyperbaric bupivacaine 0.5% with morphine 0.2 mg. Anaesthesia was successful in 103 patients with the Sprotte needle and 38 patients with the Quincke needle, and the operating conditions were considered to be excellent. Of the 104 patients in the Sprotte needle group there were ten with PDPH (9.6%), two of which were considered severe. Of the 40 patients in the Quincke needle group there were eight with PDPH (20%), three of which were considered severe. Despite the lower incidence of headache in the Sprotte needle group, this was not statistically significant (P>0.05), due to the difference in population size. We conclude that the 24 gauge Sprotte needle is associated with a comparatively low but clinically relevant incidence of headache in the obstetric population.

scholarly journals Modified S2CVA Algorithm Using Cross-Sharpened Images for Unsupervised Change Detection

2018 ◽  
Vol 10 (9) ◽  
pp. 3301 ◽  
Author(s):  
Honglyun Park ◽  
Jaewan Choi ◽  
Wanyong Park ◽  
Hyunchun Park
Keyword(s):  
Change Detection ◽  
False Alarm ◽  
False Alarm Rate ◽  
Seasonal Effects ◽  
Detection Accuracy ◽  
Difference Image ◽  
Before And After ◽  
Change Detection Algorithms ◽  
The Difference ◽  
Direction Information

This study aims to reduce the false alarm rate due to relief displacement and seasonal effects of high-spatial-resolution multitemporal satellite images in change detection algorithms. Cross-sharpened images were used to increase the accuracy of unsupervised change detection results. A cross-sharpened image is defined as a combination of synthetically pan-sharpened images obtained from the pan-sharpening of multitemporal images (two panchromatic and two multispectral images) acquired before and after the change. A total of four cross-sharpened images were generated and used in combination for change detection. Sequential spectral change vector analysis (S2CVA), which comprises the magnitude and direction information of the difference image of the multitemporal images, was applied to minimize the false alarm rate using cross-sharpened images. Specifically, the direction information of S2CVA was used to minimize the false alarm rate when applying S2CVA algorithms to cross-sharpened images. We improved the change detection accuracy by integrating the magnitude and direction information obtained using S2CVA for the cross-sharpened images. In the experiment using KOMPSAT-2 satellite imagery, the false alarm rate of the change detection results decreased with the use of cross-sharpened images compared to that with the use of only the magnitude information from the original S2CVA.

scholarly journals Spatial and seasonal effects on the delayed ionospheric response to solar EUV changes

2019 ◽  
Author(s):  
Erik Schmölter ◽  
Jens Berdermann ◽  
Norbert Jakowski ◽  
Christoph Jacobi
Keyword(s):  
Southern Hemisphere ◽  
Geomagnetic Activity ◽  
Correlation Coefficients ◽  
Seasonal Effects ◽  
Constant Delay ◽  
Average Delay ◽  
Ionospheric Response ◽  
The Difference ◽  
Longitudinal Variability ◽  
The Impact

Abstract. This study correlates different ionospheric parameters with the integrated solar EUV radiation for an analysis of the delayed ionospheric response in order to confirm previous studies on the delay and to further specify variations of the delay. Several time series for correlation coefficients and delays are presented to characterize the trend of the delay from 2011 to 2013. The impact of the diurnal variations of ionospheric parameters in the analysis on hourly resolution for fixed locations are discussed and specified with calculations in different time scales and with comparison to solar and geomagnetic activity. An average delay for TEC of ≈ 18.7 hours and for foF2 of ≈ 18.6 hours is calculated at four European stations. Through comparison with the Australian region the difference between northern and southern hemisphere is analyzed and a seasonal variation of the delay between northern and southern hemisphere is calculated for TEC with ≈ 5 ± 0.7 hours and foF2 with ≈ 8 ± 0.8 hours. The latitudinal and longitudinal variability of the delay is analyzed for the European region and a decrease of the delay from ≈ 21.5 hours at 30° N to ≈ 19.0 hours at 70° N has been found. For winter months a roughly constant delay of ≈ 19.5 hours is calculated. In this study a North-South trend of the ionospheric delay during summer month has been observed with ≈ 0.06 hours per degree in latitude. The results based on solar and ionospheric data in hourly resolution and the analysis of the delayed ionospheric response to solar EUV show the seasonal and latitudinal variations. Results also indicate the dependence on the geomagnetic activity as well as on the 11-year solar cycle.

scholarly journals Consequences of barriers and changing seasonality on population dynamics and harvest of migratory ungulates

2020 ◽  
Vol 13 (4) ◽  
pp. 595-605
Author(s):  
Bram Van Moorter ◽  
Steinar Engen ◽  
John M. Fryxell ◽  
Manuela Panzacchi ◽  
Erlend B. Nilsen ◽  
...  
Keyword(s):  
Climate Change ◽  
Population Dynamics ◽  
Population Size ◽  
Spatial Dynamics ◽  
Infrastructure Development ◽  
Negative Effects ◽  
Behavioral Avoidance ◽  
Animal Populations ◽  
The Difference ◽  
Global Threat

AbstractMany animal populations providing ecosystem services, including harvest, live in seasonal environments and migrate between seasonally distinct ranges. Unfortunately, two major sources of human-induced global change threaten these populations: climate change and anthropogenic barriers. Anthropogenic infrastructure developments present a global threat to animal migrations through increased migration mortality or behavioral avoidance. Climate change alters the seasonal and spatial dynamics of resources and therefore the effects of migration on population performance. We formulated a population model with ideal-free migration to investigate changes in population size and harvest yield due to barriers and seasonal dynamics. The model predicted an increasing proportion of migrants when the difference between areas in seasonality or carrying capacity increased. Both migration cost and behavioral avoidance of barriers substantially reduced population size and harvest yields. Not surprisingly, the negative effects of barriers were largest when the population benefited most from migration. Despite the overall decline in harvest yield from a migratory population due to barriers, barriers could result in locally increased yield from the resident population following reduced competition from migrants. Our approach and results enhance the understanding of how global warming and infrastructure development worldwide may change population dynamics and harvest offtake affecting livelihoods and rural economies.

Sign in / Sign up

Export Citation Format

Share Document