Northern Pacific Rattlesnakes (Crotalus oreganus) use thermal and structural cues to choose overwintering hibernacula

2011 ◽  
Vol 89 (11) ◽  
pp. 1084-1090 ◽  
Author(s):  
C.M. Gienger ◽  
Daniel D. Beck
Keyword(s):  
Physical Structure ◽  
Early Spring ◽  
Long Duration ◽  
Physical Composition ◽  
Social Opportunities ◽  
Northern Pacific ◽  
Crotalus Oreganus ◽  
Talus Slopes ◽  
Steep Slopes ◽  
Over Time

Hibernacula play an important role in the ecology of high-latitude snakes, and communally denning species may occupy their hibernacula for half the year or more. Because of the long duration spent at hibernacula, such sites can provide multiple benefits to snakes including shelter from lethal overwinter conditions, social opportunities, and basking sites important in thermoregulation. Adequate hibernacula seem to be limited on the landscape and individuals travel several kilometres to use and reuse specific sites. We investigate orientation, physical structure, and thermal properties of sites used as hibernacula by Northern Pacific Rattlesnakes ( Crotalus oreganus Holbrook, 1840), and compare them with random sites that appear to be similar but were not used for hibernation. Hibernacula occurred primarily on south-facing talus slopes, were oriented on less-steep slopes, and were composed of rocks that were intermediate in size to randomly occurring sites. Our results suggest that the orientation and physical composition of hibernacula allow them to be stable over time, allowing snakes to repeatedly locate the sites, as well as providing predictable overwinter refuge. Hibernacula were also warmer on the surface than north-facing random sites and provided increased basking opportunities for snakes thermoregulating in early spring after emergence from hibernation.

Loss of long-duration response to levodopa over time in PD: Implications for wearing-off

Neurology ◽  
1999 ◽  
Vol 52 (4) ◽  
pp. 763-763 ◽  
Author(s):  
M. Zappia ◽  
R. L. Oliveri ◽  
R. Montesanti ◽  
M. Rizzo ◽  
D. Bosco ◽  
...  
Keyword(s):  
Long Duration ◽  
Wearing Off ◽  
Over Time

Manipulating the Response Criterion in Visual Monitoring

1973 ◽  
Vol 15 (2) ◽  
pp. 179-185 ◽  
Author(s):  
Robert C. Williges
Keyword(s):  
Signal Detection Theory ◽  
Response Criterion ◽  
Effective Response ◽  
Visual Monitoring ◽  
Subject Design ◽  
Long Duration ◽  
Ratio Condition ◽  
Signal Detectability ◽  
Over Time ◽  
Theory Interpretation

Forty-eight subjects were required to detect long-duration brightness changes (signals) and ignore short-duration changes (nonsignals) occurring on an electroluminescent panel during a 60-min. monitoring session. Signal-to-nonsignal ratios (constant 1/9, changing 1/9 to 1/1, or constant 1/1) and signal detectability (0.3 or 0.6 sec. difference between signal and nonsignal duration) were combined factorially in a between-subject design. The changing signal-to-nonsignal ratio resulted in an intermediate level of signals correctly detected. The classical decrease in percent of signals detected over time occurred in the constant 1/9 ratio condition under both levels of signal detectability. Signal detection theory analyses were restricted to low detectable signals. A marked increase in β over the monitoring session occurred in the constant 1/9 ratio condition, whereas β remained low and relatively constant in the other signal-to-nonsignal ratio conditions. Both the limitations of a decision-theory interpretation and the implications of using changing signal-to-nonsignal ratios for manipulating the observer's effective response criterion were discussed.

Abstract 2645: Longer Ventricular Fibrillation Detection Duration Does Not Increase Rate of Undersensing: Results from the PREPARE Study

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Stephen Moore ◽  
Richard Stern ◽  
Mark L Brown ◽  
Brooke M Heubner ◽  
Jim W Johnson
Keyword(s):  
Primary Prevention ◽  
Ventricular Fibrillation ◽  
Shock Delivery ◽  
Long Duration ◽  
Increase Rate ◽  
The Times ◽  
Over Time

Background: The PREPARE study was designed to evaluate ICD detection and therapy parameters strategically selected to safely reduce all-cause shocks in patients with primary prevention indications by treating only truly sustained fast VT/VF. Electrophysiologic properties have been shown to deteriorate during long-duration VF episodes. There was concern that electrogram deterioration might result in increased undersensing (US) and delayed detection of VF. In this analysis we compared the rate of US between episodes detected with shorter (number of intervals to detect (NID) =12/16) and longer (NID=30/40) detection settings to assess whether delayed detection times for VF increased the rate of US. Methods: All induced VT/VF episodes from PREPARE patients programmed to NID 12/16 or 30/40 and sensitivity 1.2 mV were included in the analysis. US was determined automatically from the stored episode record. The numbers of US and the times from onset through initial detection and from detection to shock were computed. The rates of US over time were compared between the shorter and longer NIDs using a GEE analysis with time as the offset. Results: Seven hundred fifty six VF inductions in 432 patients from the PREPARE study were included in the analysis. There were 319 VF inductions (180 pts) with NID 12/16 and 437 VF inductions (261 pts) with NID 30/40. The average time from VF onset to shock increased from 6.0 to 9.5 seconds with the longer VFNID with no evidence of an increase in the rate of US over time. Conclusion: The longer NID delayed shock delivery by an average of 3.5 seconds but did not result in an increased rate of undersensing.

scholarly journals Spatial and temporal patterns of sediment storage and erosion following a wildfire and extreme flood

2019 ◽  
Vol 7 (2) ◽  
pp. 563-590 ◽  
Author(s):  
Daniel J. Brogan ◽  
Peter A. Nelson ◽  
Lee H. MacDonald
Keyword(s):  
Laser Scanning ◽  
Sediment Accumulation ◽  
Burn Severity ◽  
Spatial And Temporal Patterns ◽  
Channel Network ◽  
Erosion And Deposition ◽  
Long Duration ◽  
Extreme Flood ◽  
Changes Over Time ◽  
Over Time

Abstract. Post-wildfire landscapes are highly susceptible to rapid geomorphic changes, and the resulting downstream effects, at both the hillslope and watershed scales due to increases in hillslope runoff and erosion. Numerous studies have documented these changes at the hillslope scale, but relatively few studies have documented larger-scale post-fire geomorphic changes over time. In this study we used five airborne laser scanning (ALS) datasets collected over 4 years to quantify erosion and deposition throughout the channel network in two ∼15 km2 watersheds, Skin Gulch and Hill Gulch, in northern Colorado after a wildfire followed by a large, long-duration flood 15 months later. The objectives were to (1) quantify the volumes, spatial patterns, and temporal changes over time of erosion and deposition over a nearly 4-year period, and (2) evaluate the extent to which these spatially and temporally explicit changes are correlated to precipitation metrics, burn severity, and morphologic variables. The volumetric changes were calculated from a differencing of DEMs for 50 m long segments of the channel network and associated valley bottoms. The results showed net sediment accumulation after the wildfire in the valley bottoms of both watersheds, with greater accumulations in the wider and flatter valley bottoms in the first 2 years after burning. In contrast, the mesoscale flood caused large amounts of erosion, with higher erosion in those areas with more post-fire deposition. Only minor changes occurred over the 2 years following the mesoscale flood. Volume changes for the different time periods were weakly but significantly correlated to, in order of decreasing correlation, contributing area, channel width, percent burned at high and/or moderate severity, channel slope, confinement ratio, maximum 30 min precipitation, and total precipitation. These results suggest that morphometric characteristics, when combined with burn severity and a specified storm, can indicate the relative likelihood and locations for post-fire erosion and deposition. This information can help assess downstream risks and prioritize areas for post-fire hillslope rehabilitation treatments.

Evaluating the effectiveness of contour-felled log erosion barriers as a post-fire runoff and erosion mitigation treatment in the western United States

2008 ◽  
Vol 17 (2) ◽  
pp. 255 ◽  
Author(s):  
P. R. Robichaud ◽  
J. W. Wagenbrenner ◽  
R. E. Brown ◽  
P. M. Wohlgemuth ◽  
J. L. Beyers
Keyword(s):  
United States ◽  
Western United States ◽  
Return Periods ◽  
Rainfall Characteristics ◽  
Sediment Yields ◽  
Small Watersheds ◽  
Long Duration ◽  
Erosion Mitigation ◽  
Rain Events ◽  
Over Time

Between 1998 and 2002, six sites were established immediately after large wildfires in the western United States to determine the effectiveness of contour-felled log erosion barriers in mitigating post-wildfire runoff and erosion. In each pair of matched, burned, and small watersheds (1–13 ha), one was treated with contour-felled log erosion barriers and one was left untreated as a control. For 4 to 6 post-fire years, runoff and sediment yields were measured and correlated with rain properties. High-intensity rainfall produced most of the measured runoff and sediment yields except in the southern California site, where long-duration rain events produced most of the runoff and erosion. For small rain events (less than the 2-year return period for the 10-min duration), the runoff, peak flows, and sediment yields were lower in the treated watersheds than in the control watersheds, but there was no treatment effect for rain events with larger return periods. Improper installation and degradation over time reduced the effectiveness of contour-felled log erosion barriers. Rainfall characteristics and installation procedures should be carefully considered before choosing contour-felled log erosion barriers for post-fire hillslope stabilisation.

Northern Pacific rattlesnake (Crotalus oreganus) envenomation leads to ocular destruction and coagulopathy

Toxicon ◽  
2016 ◽  
Vol 119 ◽  
pp. 375
Author(s):  
Michael Touger ◽  
Denise Fernendez ◽  
Michael Lamberta ◽  
Lewis Nelson
Keyword(s):  
Northern Pacific ◽  
Crotalus Oreganus

scholarly journals Ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction

2011 ◽  
Vol 7 (4) ◽  
pp. 571-573 ◽  
Author(s):  
S. Aron ◽  
I. Timmermans ◽  
M. Pearcy
Keyword(s):  
Sexual Reproduction ◽  
Asexual Reproduction ◽  
Evolutionary Biology ◽  
Transmission Rate ◽  
Early Spring ◽  
Mating Period ◽  
Cataglyphis Cursor ◽  
Sexual And Asexual Reproduction ◽  
Over Time

An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.

The Role of Payoffs and Signal Ratios in Criterion Changes during a Monitoring Task

1971 ◽  
Vol 13 (3) ◽  
pp. 261-267 ◽  
Author(s):  
Robert C. Williges
Keyword(s):  
Signal Detection Theory ◽  
False Alarms ◽  
Signal Ratio ◽  
Monitoring Task ◽  
Decision Performance ◽  
Signal Rate ◽  
Subject Design ◽  
Long Duration ◽  
Over Time

Forty-eight subjects detected a long-duration (1.7 or 1.3 sec.) change in brightness (from a 5 ft.-l. standard to a 4 ft.-l. level) of an electroluminescent panel during a 60-min. monitoring session. Signal/nonsignal ratios (1/9 or 1/1) and payoffs (lax, neutral, or strict) were combined factorially in a between-subject design. Signal ratios affected both the percent of signal detections and the percent of false-alarm errors. When subjects monitored under the lower signal ratios, a decrease in percent of signal detections occurred over time. Payoffs affected only the percent of false alarms in the higher signal rate conditions. Signal detection theory analyses resulted in a slight decrease in d' and a marked increase in β during the watch period. The change in β was due primarily to the lower signal ratio conditions. Payoffs had no effect on subsequent β change. It was concluded that signal ratios rather than payoffs play the major role in determining decision performance in simple visual monitoring tasks.

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