Shoals and schools: back to the heuristic definitions and quantitative references

in Reviews in Fish Biology & Fisheries (2012), 22

The terms 'shoal', 'swarm' and 'school' are very frequently used in research on collective behaviours in animals. Pitcher's definitions are accepted as the authority in the field but are based on a ... [more ▼]

The terms 'shoal', 'swarm' and 'school' are very frequently used in research on collective behaviours in animals. Pitcher's definitions are accepted as the authority in the field but are based on a conceptual criterion of sociability. Without call into question the basis of these definitions, they do not provide tools to determine these behaviours quantitatively. To compare studies between populations, species, taxa or different experimental treatments, and between different authors, quantitative references are necessary. Quantitative measurements of collective behaviours can also test and validate the predictive capacity of computer models by comparing real data from nature so that different models can be compared. The first part of this paper succinctly reviews the definitions and meanings of these behaviours, with particular attention paid to quantitative aspects. This review underlines a series of conceptual confusions concerning these behavioural terms observed in the scientific literature and oral scientific communications. The second part reviews the quantitative parameters developed by biologists studying collective fish behaviours, mainly fish shoals, and by theoretical biologists and physicists studying computer modelling of collective behaviours. The parameters reviewed herein make no attempt to explain the mechanisms and causes that create a shoal, a swarm or a school, but rather try to describe these collective behaviours, and to connect local and global properties with individual and collective behaviours. Recent development over the last decade in technology, data processing capacity, cameras, and video tracking tools have provided the opportunity to obtain quantitative measures of collective dynamic behaviours in animals both rapidly and precisely. [less ▲]

Shock-capturing Methods for Mixed Flows Simulations: A Comparative Study

in Computers & Fluids (n.d.), Submitted

The shoot apical meristem of Sinapis alba L. expands its central symplasmic field during the floral transition

in Planta (2002), 215(1), 67-78

The shoot apical meristem (SAM) is functionally subdivided into zones with distinct tasks. During vegetative growth the peripheral zone of the meristem gives rise to leaf primordia that develop into ... [more ▼]

The shoot apical meristem (SAM) is functionally subdivided into zones with distinct tasks. During vegetative growth the peripheral zone of the meristem gives rise to leaf primordia that develop into dorsiventral leaves under the influence of signals from the central zone. During the floral transition the function of the SAM is altered and its peripheral zone starts to form floral structures in a specific pattern. This requires alterations in the signal networks that coordinate the activities of the peripheral and central zone of the SAM. These signal networks are partly housed in the symplasmic space of the SAM. Dye-coupling experiments demonstrate that in the superficial layer of the Sinapis alba meristem this space is radially subdivided. The cells of the central zone are coupled into a symplasmic field, which is shielded from the peripheral zone by the positional closing of plasmodesmata. In the vegetative meristems, most of these central symplasmic fields have a triangular geometry and are relatively small in size. Plants that are induced to flower by exposure to a single long day alter the geometry as well as the size of their central symplasmic field. After two subsequent days under short photoperiod the central symplasmic fields exhibit a circular form. Simultaneously. their size strongly increases both in an absolute sense and relative to the enlarging meristem. The geometric change in the fields is hypothesized to be due to recruitment of extra initial cells, required to support the increase in phyllotactic complexity. The proportional increase in field size is interpreted as an adjustment in the balance between the central and peripheral zone of the SAM, accompanying the shift from leaf production to flower formation. [less ▲]

Short administration of metformin improves insulin sensitivity in android obese subjects with impaired glucose tolerance.

in Diabetic Medicine : A Journal of the British Diabetic Association (1995), 12(11), 985-9

In a double-blind, randomized, cross-over study, the metabolic effects of a short treatment with metformin (2 x 850 mg day-1 for 2 days and 850 mg 1 h before evaluation) were compared to those of placebo ... [more ▼]

In a double-blind, randomized, cross-over study, the metabolic effects of a short treatment with metformin (2 x 850 mg day-1 for 2 days and 850 mg 1 h before evaluation) were compared to those of placebo in 15 obese subjects (BMI: 33.2 +/- 0.9 kg m-2), with abdominal distribution of adipose tissue and impaired glucose tolerance. An intravenous glucose tolerance test (0.3 g glucose kg-1) was performed after each period of treatment. Areas under the curve (AUC0-180 min) were calculated for plasma glucose, insulin, and C-peptide levels. Glucose tolerance was estimated by the coefficient of glucose assimilation (KG). Insulin sensitivity (SI) and glucose effectiveness (SG) indices were calculated using Bergman's minimal model. Insulin secretion rate (ISR) was determined by deconvolution of plasma C-peptide levels and insulin metabolic clearance rate (MCR) was estimated by dividing AUC 1SR by AUC insulin. Fasting plasma insulin levels were reduced after metformin (89.3 +/- 15.9 vs 112.4 +/- 24.3 pmol l-1; p = 0.04). AUC glucose, KG and SG were similar in both tests. However, AUC insulin was reduced (39.7 +/- 6.5 vs 51.8 +/- 10.4 nmol min l-1; p = 0.02), while SI (6.98 +/- 1.14 vs 4.61 +/- 0.42 10(-5) min-1 pmol-1 l; p = 0.03) and insulin MCR (715 +/- 116 vs 617 +/- 94 ml min-1 m-2; p = 0.03) were increased after metformin. The demonstration that metformin rapidly improves insulin sensitivity should encourage further research to evaluate the long-term effects of metformin in android obese subjects with impaired oral glucose tolerance. [less ▲]

Short and long-term prognosis of small acute myocardial infarction : a natural history study

in European Heart Journal Supplements : Journal of the European Society of Cardiology (1987), 8(suppl.2), 110

A short C-rich PNA fragment capable to form novel G-quadruplex-PNA complexes

in Nucleic Acids Symposium Series (2008), 52

In this work we investigated the interaction between the short ac(4)a C-rich peptide nucleic acid (PNA) probe and two intramolecular G-quadruplex targets having the same G-tetrad core, but different ... [more ▼]

In this work we investigated the interaction between the short ac(4)a C-rich peptide nucleic acid (PNA) probe and two intramolecular G-quadruplex targets having the same G-tetrad core, but different folding topologies. The T(G(4)T)(3)G(4)T and the recently reported tetra-end-linked-(TG(4)T)(4) G-rich oligonucleotides (GROs) were chosen and synthesized for this study. UV, CD, and MS experiments revealed the formation of novel 1:1 G-quadruplex-PNA complexes besides the expected DNA-PNA heteroduplexes [less ▲]

Short communication: correlations of marker-assisted breeding values with progeny-test breeding values for eight hundred ninety-nine French Holstein bulls.

in Journal of Dairy Science (2008), 91(6), 2520-2

French artificial insemination companies have been running a marker-assisted selection program since 2001 to determine which young bulls should be progeny tested. A first batch of 899 Holstein sires ... [more ▼]

French artificial insemination companies have been running a marker-assisted selection program since 2001 to determine which young bulls should be progeny tested. A first batch of 899 Holstein sires receiving their first proofs based on progeny daughters has been studied. Estimated breeding values with or without marker information were computed based on information available in April 2004, and correlated to daughter yield deviations available in 2007 for production traits. Marker-assisted estimated breeding values presented greater correlations with daughter yield deviations than those calculated using only pedigree index. The average improvement in correlation was 0.043 and ranged from +0.001 for protein yield to +0.103 for fat percentage. This gain was based on the initial and suboptimal conditions of the program and is expected to increase in the coming years because of several improvements implemented since the start of the marker-assisted selection program. [less ▲]

Short communication: Genetic evaluation of milking speed for brown Swiss dairy cattle in the United States

in Journal of Dairy Science (2007), 90(2), 1021-1023

Genetic parameters and relative breeding values were estimated for milking speed of US Brown Swiss dairy cattle. Owner-recorded milking-speed scores on a scale of 1 (slow) to 8 (fast) were collected by ... [more ▼]

Genetic parameters and relative breeding values were estimated for milking speed of US Brown Swiss dairy cattle. Owner-recorded milking-speed scores on a scale of 1 (slow) to 8 (fast) were collected by the Brown Swiss Association as part of its linear type appraisal program starting in 2004. Data were 7,366 records for 6,666 cows in 393 herds. The pedigree file included information for 21,458 animals born in 1985 or later. Six unknown-parent groups that each included 4 birth years were defined. The model included fixed effects for herd appraisal date and parity-lactation stage and random effects for permanent environment, animal, and error. Within parity (1, 2, and >= 3), 6 groups were defined: unknown calving date, four 90-d lactation stages, and lactations with > 400 d in milk. Heritability of 0.22 and repeatability of 0.42 were estimated by average-information REML; residual variance was 1.13. Little trend in estimated breeding value was found for cows born from 1999 through 2002. Although solutions increased with lactation stage for first-parity cows by 0.37, no clear trend was found for later parities. Genetic evaluations for milking speed were expressed as relative breeding values with a mean of 100 and a standard deviation of 5. The 121 bulls with >= 10 daughters had milking speed evaluations that ranged from 83 to 112 and had correlations of 0.56 with productive life evaluations and -0.40 with somatic cell score evaluations. The association of faster milking speed with lower somatic cell score was not expected. The moderate heritability found for milking speed indicates that the evaluations (first released in May 2006) should be useful in detecting bulls with slow-milking daughters. [less ▲]

Short communication: Genetic variation of saturated fatty acids in Holsteins in the Walloon region of Belgium

in Journal of Dairy Science (2010), 93

Random regression test-day models using Legendre polynomials are commonly used for the estimation of genetic parameters and genetic evaluation for test-day milk production traits. However, some ... [more ▼]

Random regression test-day models using Legendre polynomials are commonly used for the estimation of genetic parameters and genetic evaluation for test-day milk production traits. However, some researchers have reported that these models present some undesirable properties such as the overestimation of variances at the edges of lactation. Describing genetic variation of saturated fatty acids expressed in milk fat might require the testing of different models. Therefore, 3 different functions were used and compared to take into account the lactation curve: (1) Legendre polynomials with the same order as currently applied for genetic model for production traits; 2) linear splines with 10 knots; and 3) linear splines with the same 10 knots reduced to 3 parameters. The criteria used were Akaike’s information and Bayesian information criteria, percentage square biases, and log-likelihood function. These criteria indentified Legendre polynomials and linear splines with 10 knots reduced to 3 parameters models as the most useful. Reducing more complex models using eigenvalues seemed appealing because the resulting models are less time demanding and can reduce convergence difficulties, because convergence properties also seemed to be improved. Finally, the results showed that the reduced spline model was very similar to the Legendre polynomials model. [less ▲]

Short communication: Pasteurization of milk abolishes bovine herpesvirus 4 infectivity.

in Journal of Dairy Science (2005), 88(9), 3079-83

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus highly prevalent in the cattle population that has been isolated from the milk and the serum of healthy infected cows. Several studies reported the ... [more ▼]

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus highly prevalent in the cattle population that has been isolated from the milk and the serum of healthy infected cows. Several studies reported the sensitivity and the permissiveness of some human cells to BoHV-4 infection. Moreover, our recent study demonstrated that some human cells sensitive but not permissive to BoHV-4 support a persistent infection protecting them from tumor necrosis factor-alpha-induced apoptosis. Together, these observations suggested that BoHV-4 could represent a danger for public health. To evaluate the risk of human infection by BoHV-4 through milk or serum derivatives, we investigated the resistance of BoHV-4 to the mildest thermal treatments usually applied to these products. The results demonstrated that milk pasteurization and thermal decomplementation of serum abolish BoHV-4 infectivity by inactivation of its property to enter permissive cells. Consequently, our results demonstrate that these treatments drastically reduce the risk of human infection by BoHV-4 through treated milk or serum derivatives. [less ▲]