Seasonal, inverse cycling of length- and age-at-recruitment in the diadromous gobies Sicydium punctatum and Sicydium antillarum in Dominica, West Indies

1995 ◽  
Vol 52 (7) ◽  
pp. 1535-1545 ◽  
Author(s):  
Kim N. I. Bell ◽  
Joseph A. Brown ◽  
Pierre Pepin

We report on an 18-month field study of temporal pattern and interrelationships of size- and age-at-recruitment (to fresh waters) for two diadromous hill-stream gobies in Dominica, West Indies (15°30′N, 61°25′W). Recruitment is panseasonal in Sicydium punctatum and Sicydium antillarum and supports a directed fishery similar to other goby fry fisheries. We found both size and age of recruits to vary seasonally, but the relationship of size to age is complex. Although positively related within lunar-monthly recruiting cohorts, the overall relationship of size and age was poor because seasonal variation in size is out of phase with age. Among recruiting cohorts, mean (or predicted) size and age are negatively correlated. Recruitment (fishery yield) also varies seasonally, in phase with size and out of phase with age. Peak fishery yields coincide with the youngest, but largest, recruits; low yields coincide with the reverse, implicating growth rate variations in fishery yield. This is the first such report of systematic seasonal variation in age-at-recruitment. Given these findings, size- and age-at-recruitment (here similar to settlement or metamorphosis) should not be assumed invariant, even for tropical fishes.

1975 ◽  
Vol 2 (2) ◽  
pp. 101-118
Author(s):  
Marlene Hamilton

This paper seeks to investigate possible links between Cambridge examination results in the General Certificate of Education "O" and "A" level examinations over the years, and the annual Jamaican graduate output from the University of the West Indies. Although all faculties are considered, the main interest lies in numbers of graduates from the faculties of Natural Sciences, Engineering, Agriculture and Medicine, linked with passes gained in science subjects at both "O" and "A" level GCE examinations.


Neurology ◽  
2020 ◽  
pp. 10.1212/WNL.0000000000011258
Author(s):  
Longting Lin ◽  
Jianhong Yang ◽  
Chushuang Chen ◽  
Huiqiao Tian ◽  
Andrew Bivard ◽  
...  

ObjectiveTo test the hypothesis that acute ischemic patients with poorer collaterals would have faster ischemic core growth, we included 2 cohorts in the study, cohort 1 of 342 patients for derivation and cohort 2 of 414 patients for validation purpose.MethodsAcute ischemic stroke patients with large vessel occlusion were included. Core growth rate was calculated by the following equation: Core growth rate = Acute core volume on CTP/Time from stroke onset to CTP. Collateral status was assessed by the ratio of severe hypoperfusion volume within the hypoperfusion region of CTP. The CTP collateral index was categorized in tertiles; for each tertile, core growth rate was summarized as median and inter-quartile range. Simple linear regressions were then performed to measure the predictive power of CTP collateral index in core growth rate.ResultsFor patients allocated to good collateral on CT perfusion (tertile 1 of collateral index), moderate collateral (tertile 2), and poor collateral (tertile 3), the median core growth rate was 2.93 mL/h (1.10–7.94), 8.65 mL/h (4.53–18.13), and 25.41 mL/h (12.83–45.07) respectively. Increments in the collateral index by 1% resulted in an increase of core growth by 0.57 mL/h (coefficient = 0.57, 95% confidence interval = [0.46, 0.68], p < 0.001). The relationship of core growth and CTP collateral index was validated in cohort 2. An increment in collateral index by 1% resulted in an increase of core growth by 0.59 mL/h (coefficient = 0.59 [0.48–0.71], p < 0.001) in cohort 2.ConclusionCollateral status is a major determinant of ischemic core growth.


Parasitology ◽  
1975 ◽  
Vol 70 (1) ◽  
pp. 103-118 ◽  
Author(s):  
A. R. Mead-Briggs ◽  
J. A. Vaughan ◽  
B. D. Rennison

Samples of rabbits were obtained throughout each month over the 4-year period 1967–70. All fleas were removed, sexed and counted and the reproductive condition of the rabbits recorded. Rabbit fleas Spilopsyllus cuniculi (Dale) were present on both sexes of rabbit at all times of the year. In each year significantly high numbers of fleas were found on the rabbits in January, February, March and April and significantly low numbers in August, September and October. Mean flea counts were significantly higher on female rabbits than on males during April, May and June. During the rest of the year counts from each sex of host did not differ significantly. There were significant differences in flea numbers between years. More female than male fleas were found on both sexes of host throughout the year. The rabbit population sampled is shown to be typical of post-myxomatosis populations with regard to breeding performance and juvenile mortality. The relationship of the observed patterns of change in flea numbers to host and flea breeding and to host behaviour, population size and structure is discussed.


1959 ◽  
Vol 53 (3) ◽  
pp. 358-368 ◽  
Author(s):  
Janet P. Tibbits

The relationship between cortical area and fibre area has been examined in the N/N, N/ +, + / +, + /nr and nr/nr genotypes of the New Zealand Romney, using skin biopsies taken at birth, 1, 3 and 16 months of age. The presence of the nr gene was shown to reduce significantly the relative cortical area. Within the genotypes there was an increase in relative cortical area with increasing age and in two-tooth ewes of N/N and N/ + there was an increase in relative cortical area in winter compared to summer.Fibre growth rates in length for primaries and for prenatal and post-natal secondaries were found for lambs between 1 and 3 months and for 16-monthold ewes. In N/N, N/+ and nr/nr primary fibre growth tended to be increased and post-natal secondary fibre growth tended to be decreased relative to + / + values.In both cortical area and fibre growth rate the greatest genotypic effect was shown by the primary fibres.Some estimates of cortical volume have been made by combining the information on cortical area and fibre growth rate and the relationship of these factors to follicle density and mean fibre area has been discussed. Finally, an indication has been given of how the associations of all these four factors might be usefully examined in some British breeds.


1955 ◽  
Vol 6 (2) ◽  
pp. 308 ◽  
Author(s):  
PG Schinckel

Observations are reported on factors affecting the ratio of secondary to primary follicles (SJP) in a flock of Merino sheep.It was found that all follicles were initiated prior to birth but that the number which finally came to maturity (production of fibre) was significantly affected by birth weight and growth from birth to 1 month. Growth at later ages appeared to be unimportant. There was a significant correlation (r = +0.29) between birth weight and log potential S/P at birth. This is interpreted to indicate that while pre-natal growth conditions affect the number of follicles initiated, other factors are also of considerable importance. It is concluded that the larger animals at birth also have a greater total number of primary follicles than smaller animals. It is further concluded that this difference in total primary follicles results primarily from differences in size a t the 90th day of pre-natal life rather than from differences in density a t that time.


2016 ◽  
Vol 26 (3) ◽  
pp. 277-300 ◽  
Author(s):  
Long W. Lam ◽  
Raymond Loi ◽  
Ka Wai Chan ◽  
Yan Liu

ABSTRACT:Given the importance of voice in ethical leadership theory, we analyze the relationship of ethical leadership to employee voice and the relationship of voice to exit intentions. Building on the theory of work engagement, we further hypothesize that cognitive engagement mediates these proposed relationships. To test these propositions, we conduct a field study to relate ethical leadership of supervisors, measured at time 1, to employees’ cognitive job engagement, measured at time 2. The analyses show that the relationship between these variables can account for supervisory ethical leadership’s association with employee voice and exit intentions. In a supplementary study using a different sample, we find that supervisory ethical leadership is related to exit intentions through voice. We discuss how these findings contribute to the literature on ethical leadership, employee voice, and exit.


2015 ◽  
Vol 10 (11) ◽  
pp. 149 ◽  
Author(s):  
Narman Kuzucu

<p>Dividend policy of firms is one of the most controversial issues of theoretical finance. This paper aims to investigate the firm-level factors influencing the dividend decisions of firms from an emerging market. We examined eight-year panel data for the period from 2006 to 2013 from the Turkish stock market (Borsa Istanbul). The results show that financial leverage, size, growth rate, age, profitability, ownership structure and P/E ratio are statistically significant. The relationship of leverage, growth rate, profitability and family control with dividends is negative, whereas the relationship of size, age and P/E ratio is positive. Therefore, firms with higher debt ratios / growth rates / higher earnings are likely to retain more of their earnings. The empirical evidence from the Turkish stock market shows that the maturity hypothesis proposed by Grullon, Michaely and Swaminathan (2002) best explains the dividend behaviors of firms. Accordingly, as a firm matures, the availability of profitable projects reduces and earnings decrease. As the investment opportunities reduce, the need for resources decreases and the firm increases dividend payouts to shareholders.</p>


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