125,726 research outputs found
A fixed energetic ceiling to parental effort in the great tit?
No full text1. To elucidate the links between avian brood size, parental effort and parental investment, we measured daily energy expenditure (DEEfem), condition (residuals of mass on tarsus) and feeding rate in female great tits Parus major L. rearing broods in which the number of young was either reduced, unmanipulated or enlarged. 2. Female condition was negatively correlated with manipulation when measured at the nestling age of 8 days (measured during the day), which suggests a shift in allocation from self-feeding to chick-feeding. However, there was no detectable manipulation effect on condition measured at the nestling age of 12 days (measured during the night). Either female condition was only affected by manipulation in the early nestling phase or the females adjusted their diurnal mass trajectory in response to brood size manipulation. More detailed data are required to verify this point. There were no indications of a fitness cost associated with the condition during the day, but condition at night was positively related to winter survival. Since manipulation only affected condition during the day, there was no link between manipulation and winter survival. 3. The duration of the working day was not affected by manipulation and female feeding rate tended to flatten off with manipulated brood size. Similarly, brood reduction resulted in a lower DEEfem, whilst brood enlargement had no effect. This suggests that females worked at an energetic ceiling when rearing an unmanipulated brood. However, the level of this 'ceiling' in DEEfem was not fixed: it differed between years. This leads us to conclude that the observed ceiling was imposed by extrinsic factors (e.g. available foraging time) and not by an intrinsic factor such as maximum energy assimilation rate. We hypothesize that time limitation was the cause for the observed ceiling in energy expenditure and that the annual variation in the level of this ceiling was due to annual variation in ambient temperature. 4. A cost of reproduction was previously demonstrated in this population: brood enlargement caused a reduction in the incidence of second clutches. However, since DEEfem did not differ between control and enlarged broods, we judge it unlikely that daily energy expenditure is a general predictor for parental investment. [KEYWORDS: clutch size; condition; energy expenditure; cost of reproduction; parental effort; Parus major L. Starlings sturnus-vulgaris; kestrel falco-tinnunculus; parus-major; brood size; clutch size; blue tits; food availability; feeding frequency; field metabolism; trade-offs]
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Penerapan model verhulst pada populasi penduduk Indonesia
No full textModel logistik pertumbuhan populasi Verhulst merupakan model yang memasukkan batas untuk populasinya sehingga jumlah populasi dengan model ini tidak akan tumbuh secara tak terhingga. Persamaan model logistik Verhulst ini merupakan persamaan diferensial otonom. Maka nilai equilibrium diperoleh ketika dN/dt=0, yaitu N=0 dan N=a/b. Ketika N=0 merupakan titik equilibrium tidak stabil, sedangkan ketika N=a/b merupakan titik equilibrium stabil. Verhulst menjelaskan parameter a (laju pertumbuhan) dan a/b (carrying capacity) dapat diperkirakan dari jumlah populasi N(t) untuk tiga waktu yang berbeda dalam rentang waktu pengambilan data sama. Dengan simulasi menggunakan data populasi penduduk Indonesia, dari enam kali percobaan yang telah dilakukan berdasarkan penjelasan Verhulst ini, hasil yang diperoleh menunjukkan bahwa : laju pertumbuhan (a) semakin besar apabila ∆t rentang waktu pengambilan datanya semakin besar, nilai carrying capacity (batas populasi maksimum) semakin besar apabila ∆t rentang waktu pengambilan datanya semakin kecil, dan tidak dapat dikatakan bahwa untuk ∆t rentang waktu pengambilan data semakin besar, hasil prediksi populasi akan semakin baik. Model logistik pertumbuhan populasi Verhulst cukup baik dan cukup realistis dalam memprediksi suatu populasi, namun untuk jangka waktu yang tidak terlalu panjang
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
SPT 2004 - Symmetry and Perturbation Theory
No full textSPT 2004
Symmetry and Perturbation Theory
30 May - 6 June 2004, Cala Gonone (Sardinia, Italy)
Scientific Committee:
S. Abenda (Bologna, I), D. Bambusi (Milano, I), G. Cicogna (Pisa, I),
A. Degasperis (Roma, I), G. Gaeta (Milano, I), V. Kuznetsov (Leeds, UK),
G. Marmo (Napoli, I), P. Olver (Minneapolis, USA), J.P. Ortega (Besançon, F),
S. Rauch (Linkoping, S), E. Sousa Dias (Lisboa, P), S. Terracini (Milano, I),
F. Verhulst (Utrecht, NL), S. Walcher (Aachen, D), B. Zhilinskii (Dunquerque, F)
Organizing Commitee:
A. Degasperis (Roma), G. Gaeta (Milano), B. Prinari (Lecce), S. Terracini (Milano)
The conference is the fifth of a series begun in 1996. The principal aim of the series of conference is to join together researchers from areas of pure and applied mathematics, physics and chemistry to present their most recent and innovative achievements in the field of symmetries, perturbation and integrable systems.
Conference proceedings are published by World Scientific
[coated stock card] P.B. Van Moorleghem, agent van affairens en proprietaris, Hoogpoort N° 40, te Gend, belast zich met het stellen van Rempla-canten en Substituanten en neemt de Kans aen om tegen eenen zekeren prys voor de Lotelingen iimmers uyt te trekken, en die, in het lot vallende, door het stellen van mannen te zynen koste vry te maken.
No full textP. B. Van Moorleghem, Gent. Makelaar in militaire plaatsvervangingen. Siercartouche met links en rechts de loottrommel, de hoorn des overvloeds, acanthusbladeren. Binnen de cartouche een tafereel van personen aan tafel waarvoor een naakte loteling gekeurd wordtP. B. Van Moorleghem, Gent. Makelaar in militaire plaatsvervangingen. Siercartouche met links en rechts de loottrommel, de hoorn des overvloeds, acanthusbladeren. Binnen de cartouche een tafereel van personen aan tafel waarvoor een naakte loteling gekeurd wordtBijzondere collectiesVliegende BladenOorspronkelijke map in Collectie Vliegende Bladen: Moorleghem, Van. P.B.Overgebracht naar een aparte collectie porseleinkaarten op 06/2016Oud plaatsnummer BIB.VLBL.FI.M.10
Coupling lifespan and aging?:The age at onset of body mass decline associates positively with sex-specific lifespan but negatively with environment-specific lifespan
No full textWhether lifespan scales to age-associated changes in health and disease is an urgent question in societies with increasing lifespan. Body mass is associated with organismal functioning in many species, and often changes with age. We here tested in zebra finches whether two factors that decreased lifespan, sex and poor environmental quality, accelerated the onset of body mass declines. We subjected 597 birds for nine years to experimentally manipulated foraging costs (harsh = H, benign = B) during development (small vs large brood size) and in adulthood (easy vs hard foraging conditions) in a 2 x 2 design. This yielded four treatment combinations (HH, HB, BH, BB) for each sex. Harsh environments during development and in adulthood decreased average body mass additively. The body mass aging trajectory showed a short steep increase in early adulthood, followed by a plateau and then a decline after 5 years. This decline occurred in all groups except for HB females, which gained mass until death. Surprisingly, the onset of body mass decline was earlier in experimental groups with a longer lifespan. In contrast, the onset of body mass decline was one year earlier in females, which lived two months (4%) shorter than males. Thus, the onset of body mass aging associated positively with the sex-specific differences in lifespan, but negatively with the environmental modulation of lifespan. Thus, body mass aging trajectories did not generally scale to lifespan, and we discuss the possible causes and implications of this finding
Glucocorticoid-temperature association is shaped by foraging costs in individual zebra finches
No full textGlucocorticoid (GC) levels vary with environmental conditions, but the functional interpretation of GC variation remains contentious. A primary function is thought to be metabolic, mobilizing body reserves to match energetic demands. This view is supported by temperature-dependent GC levels, although reports of this effect show unexplained heterogeneity. We hypothesized that the temperature effect on GC concentrations will depend on food availability through its effect on the energy spent to gather the food needed for thermoregulation. We tested this hypothesis in zebra finches living in outdoor aviaries with manipulated foraging conditions (i.e. easy versus hard), by relating within-individual differences in baseline GCs between consecutive years to differences in ambient temperature. In agreement with our hypothesis, we found the GC-temperature association to be significantly steeper in the hard foraging environment. This supports the metabolic explanation of GC variation, underlining the importance of accounting for variation in energy expenditure when interpreting GC variation
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