Successive Splits Research Articles

The Relationship between Stroke Metrics, Work Rate and Performance in Slalom Kayakers

The purpose of this study was to assess the relationship between work rate, stroke metrics, and performance in whitewater slalom. Twelve Spanish, nationally competitive whitewater slalom kayakers took part in a simulated competition while using an instrumented kayak paddle to record stroke metrics over a simulated race, total duration and sectional splits. Performance time was highly correlated to overall power output (r2 = 0.511, p < 0.001), where kayakers demonstrated a positive pacing strategy with power output significantly decreasing over successive sectional splits (158 ± 40, 112 ± 32 and 65 ± 33 W, p < 0.001). This resulted in an increased stroke duration (p < 0.001), time to peak force (p < 0.001), a decrease in stroke peak force (p < 0.001), and rate of peak force development (p < 0.001) over elapsed time. As such, work rate is deemed an objective metric to monitor performance, prescribe training, and ascertain optimal pacing strategies in canoe slalom.

PCN1 PROGNOSTIC FACTORS ASSOCIATED WITH REAL WORLD PROGRESSION-FREE SURVIVAL (PFS) AND OVERALL SURVIVAL (OS) IN PATIENTS WITH BRAF V600 MUTATION-POSITIVE ADVANCED MELANOMA TREATED WITH COBIMETINIB COMBINED WITH VEMUIRAFENIB, USING SURVIVAL DECISION TREE TECHNIQUE

Treatment with cobimetinib (C) combined with vemurafenib (V) was used in France in 2015 through a ‘Temporary Authorization for Use’ program (TAU, pre-approval access) and it was marketed on January 2016 for adult patients (pts) with BRAF V600 mutation-positive (+) advanced melanoma. This study aimed to provide real-world effectiveness for a relevant time in pts previously registered in the C TAU. This non-interventional, ambispective, multicenter French study was conducted from 10/2016 to 08/2018 in pts with BRAF V600+ advanced melanoma, with an 18-month follow-up after inclusion. To search for factors associated with survival results (OS and PFS evaluated by Kaplan-Meier method), survival trees were grown on the analysed pts with all baseline covariates. Two control fixed parameters (a maximum depth of 3 successive splits and a minimum of 60 pts in each terminal node) were used in the analyses. Mean age of the 185 evaluable pts was 57±13 years; 63% were men. 159 pts (88%) had disease stage IV. Eastern Cooperative Oncology Group (ECOG) score was ≥2 in 10% of pts (11/114). Prior therapies included surgery (90%), radiation therapy (28%). Median C duration was 14.0 months (mo) (interquartile range: 5.8-18.7). Median OS was 16.1 mo [95%CI 12.5-20.7] and median PFS was 7.3 mo [95%CI 5.2-8.4]. Disease stage IV-M1c (or missing; n=118 pts) was shown to be associated with a shorter median OS, 9.3 mo. Identical groups of pts were shown for the factors associated to PFS: disease stage IV-M1c (or missing; n=118 pts) was shown to be associated with a shorter median PFS compared to other pts (n=67): 4.5 mo and 12.0 mo, respectively. Using survival decision trees, disease stage IV-M1c was shown to be the factor associated with shorter OS and PFS.

The effect of sex and performance level on pacing in cross-country skiers: Vasaloppet 2004‐2017

BackgroundPacing, defined as percentage changes of speed between successive splits, has been extensively studied in running and cycling endurance sports; however, less information about the trends in change of speed during cross-country (XC) ski racing is available. Therefore, the aim of the present study was to examine the effect of performance (quartiles of race time (Q), with Q1 the fastest and Q4 the slowest) level on pacing in the Vasaloppet ski race, the largest XC skiing race in the world. MethodsFor this purpose, we analyzed female (n = 19,465) and male (n = 164,454) finishers in the Vasaloppet ski race from 2004 to 2017 using a one-way (2 sexes) analysis of variance with repeated measures to examine percentage changes of speed between 2 successive splits. Overall, the race consisted of 8 splits. ResultsThe race speeds of Q1, Q2, Q3, and Q4 were 13.6 ± 1.8, 10.6 ± 0.5, 9.2 ± 0.3, and 8.1 ± 0.4 km/h, respectively, among females and 16.7 ± 1.7, 13.1 ± 0.7, 10.9 ± 0.6, and 8.9 ± 0.7 km/h, respectively, among males. The overall pacing strategy of finishers was variable. A small sex × split interaction on speed was observed (η2 = 0.016, p < 0.001), with speed difference between sexes ranging from 14.9% (Split 7) to 27.0% (Split 1) and larger changes in speed between 2 successive splits being shown for females (p < 0.001, η2 = 0.004). A large performance × split interaction on speed, with Q1 presenting the smallest changes of speed between splits, was shown for females (η2 = 0.149, p < 0.001) and males (η2 = 0.169, p < 0.001). ConclusionMale and fast XC skiers are more even pacers. Coaches and athletes should develop tailored sex- and performance-level pacing strategies; for instance, they should advise fast XC skiers to start fast and maintain their speed, rather than starting slowly and trying to make up time by going faster at times during the race.

Shape and fission instabilities of ferrofluids in non-uniform magnetic fields

We study static distributions of ferrofluid submitted to non-uniform magnetic fields. We show how the normal-field instability is modified in the presence of a weak magnetic field gradient. Then we consider a ferrofluid droplet and show how the gradient affects its shape. A rich phase transition phenomenology is found. We also investigate the creation of droplets by successive splits when a magnet is vertically approached from below and derive theoretical expressions which are solved numerically to obtain the number of droplets and their aspect ratio as a function of the field configuration. A quantitative comparison is performed with previous experimental results, as well as with our own experiments, and yields good agreement with the theoretical modelling.

Phylogeny and origins of holoparasitism in Orobanchaceae

Orobanchaceae are a family of angiosperms that range from fully autotrophic and free-living to completely heterotrophic and dependent on their hosts (holoparasites). Most of the ca. 2060 species are hemiparasites that photosynthesize throughout all or part of their life cycles. Certain family members are ecologically important due to direct impacts on community biomass and diversity, plant-herbivore interactions, and nutrient cycling. Other members are among the most economically damaging weeds in the world. Multiple trophic transitions within this family make it ideal for studying molecular evolutionary and physiological changes that accompany the evolution of parasitism. • To establish a phylogenetic framework for such work, we substantially increased taxonomic sampling at loci for which a significant amount of data already existed (nuclear ITS and PHYA, plastid matK and rps2) and added data from the low-copy nuclear locus, PHYB. • The data provide strong support for relationships among six major clades and for the position of Brandisia hancei Hook. f. The positions of Boschniakia himalaica Hook. f. & Thomson, Centranthera cochinchinensis (Lour.) Merr., Mannagettaea hummelii Harry Sm., and Pterygiella nigrescens Oliv. are confirmed or suggested for the first time. • There is a single origin of parasitism, and from within the hemiparasites, holoparasitism has originated three times. Moving from the base to the tips of the Orobanchaceae tree, the successive major splits within the parasitic clade are: Cymbarieae + the rest; Orobancheae + the rest; Brandisia + the rest; Rhinantheae + the rest; and Pedicularideae + Buchnereae.

The phylogenetic interpretation of biological surveys

The ecological attributes of two species may be similar through convergent evolution or common ancestry. The extent of similarity by descent can be evaluated by comparing them with their most closely‐related outgroup in a given phylogeny. I describe a method of nested sister‐group analysis for estimating ecological similarity based on landscape features or on co‐distribution. The phylogeny is dissected into triplets, each comprising two sister taxa and their outgroup. For a triplet at any phylogenetic level, the similarity of sister groups with respect to some given character can be compared with their joint similarity to the outgroup to give a single test of similarity by descent. Each comparison is independent, and the full set of triplets provides a complete accounting of phylogenetic variation at all levels. This procedure was applied to 188 moderately abundant species of dicots in two independent surveys from adjoining districts of midland England, supplemented by physical surveys of landscape attributes obtained from digitized maps of the same districts. The co‐distribution of sister species was consistently more positive than the co‐distribution of random species pairs, demonstrating the existence of a phylogenetic signal at some level. When sister species are compared with their most closely‐related outgroup, however, neither landscape attributes nor co‐distribution showed any overall similarity arising from common ancestry, in the sense that ecological attributes are not generally conserved after lineage splitting. Instead, the distribution of similarity is strikingly similar to random data. The lack of ecological similarity between closely‐related groups was attributed to rapid character change at or shortly after the splitting of lineages, coupled with a lack of correlation between successive lineage splits.

Evidence for dimerization in the ?2-adrenergic receptor from the evolutionary trace method

The evolutionary trace method (Lichtarge et al., Proc Natl Acad Sci USA 1996, 93, 7507) was applied to the adrenergic-receptor sequences. The conserved and “conserved-in-class” residues were determined for successive splits along the phylogenetic tree. These residues were then plotted on the internal and external faces of a model of the β2-adrenergic receptor. The adrenergic-receptor model was constructed using knowledge of the helix–helix packing angles in the cryoelectron microscopy structure of rhodopsin and the ideal ridges-in-grooves helix packing patterns known to reproduce these angles. Two clusters were observed on the external (lipid-facing) surface of the receptor model: a major one on helices 5 and 6 and a minor one on helices 2 and 3. The importance of some of the residues on helices 5 and 6 was confirmed by site-direceted mutagenesis. In contrast, very few residues were plotted on the external face of helices 1, 4, or 7. The major cluster is consistent with the dimerization interface in G-protein-coupled receptor domain-swapped dimers, which is proposed to occur between helices 5 and 6. The minor cluster is of unknown function. The clusters on the internal faces contain the known ligand-binding sites, as determined by site-directed mutagenesis. In particular, there is a line of conserved residues on helices 2–7 at a depth of about 14 Å. On helices 2 and 3, and on 6 and 7, the cluster extends considerably deeper than the known binding site. These deeper clusters contain the conserved DRY and NPXXY motifs on helices 3 and 7, respectively, and so are probably related to receptor activation. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 74: 371–379, 1999

Coal seam splits and transgressive-regressive coal couplets: A key to stratigraphy of high-frequency sequences

A model of the stratigraphy of sequences in coal, based on a subsurface case study of the coal-bearing Lower Cretaceous Mannville Group of Canada, posits basinward progressive splitting patterns of thick, regionally extensive paralic coal seams. Successive splits bounded by transgressive-regressive coal-seam couplets are interpreted to be fourth-order sequences produced in single base-level cycles. Stacked in a progradational pattern, these fourth-order sequences in turn form third-order sequences. Thick, regional seams form on top of a prograding platform by amalgamation of several fourth-order sequences. Vertical profiles of coal properties (geochemistry, petrology, and palynology) in the lower and upper leaves of a split seam which constitute a transgressive-regressive couplet would yield characteristic signatures revealing their transgressive and regressive nature, respectively.

Internodons as equivalence classes in genealogical networks: building-blocks for a rigorous species concept

Among the options suggested in phylogenetic systematics to solve the species problem is the Hennigian or internodal species concept. This concept interprets species as parts of the genealogical network of individual organisms between two successive permanent splits or between a permanent split and an extinction event. Though this option is at present not favoured by phylogeneticists, we believe that, to solve the species problem, there is no alternative to finding a satisfactory partition of the genealogical network. In previous work a formal definition has been developed of Hennigian or internodal species (called internodons here), based on a logical relation between individual organisms. In this paper, we prove that this definition indeed partitions genealogical networks exhaustively into mutually exclusive entities, by showing that the defining relation is an equivalence relation. Although internodons should not themselves be seen as species, they are essential building-blocks for any satisfying species concept.

The Death of Hutterite Culture: A Rejoinder

IN THE FALL 1972 ISSUE of Phylon, James S. Frideres develops the central thesis that various Canadian Provincial Governments are bringing about the death of the Hutterite He charges the Provincial Governments of Alberta, Saskatchewan and Manitoba with having consciously and systematically attempted to destroy the social and cultural framework of that culture.1 As reasons for this alleged cultural genocide Frideres mentions hostilities which originated in the passivistic belief system of Hutterites, which during the Second World War led to the spawning of such Legislation as the Alberta Land Sales Prohibition Act superseded later by the Communal Property Act of the late 1940's. More recent hostilities against Hutterites, according to Frideres, center around economic issues. He mentions the alleged detrimental effect which Hutterite colonies are supposed to have on local communities, causing their economic and social decline. There is furthermore the belief, that the Hutterites would buy up all the agricultural land and drive all other farmers out.2 In analyzing how the death of the Hutterite culture is being brought about, Frideres first develops a set of religious and socio-cultural imperatives which are seen as crucial to the survival of the group. He mentions a highly internalized Protestant Ethic which in combination with certain religious beliefs compels Hutterites to remain tillers of the soil, to be subordinate to the group, to accept transiency as a way of life and to procreate without the intervention of artificial means.3 Further structural imperatives for survival are found in the division of labor and the differentation of status in Hutterite colonies which in combination with the natural increase of Hutterites makes successive splits of colonies necessary because the division of labor in combination with the status stratification limits the population size of any colony. Frideres asserts that the aforementioned Provincial Governments consciously manipulate these religious and structured imperatives of Hutterite existence with the intent of bringing about the demise of this culture. This he claims is done in three ways. First, freedom of movement and land acquisition is restricted and therefore Hutterites cannot settle close to each other to share expensive machinery. Consequently, each colony is forced to invest large sums of money in such equipment. Second, by delaying the decision to allow them to split, the internal problems that confront the individual members are exaggerated. Third,

Testing of Evolutionary Independence in Simulated Phylogenetic Trees

Astolfi, P. (Istituto di Genetica, Università di Pavia 27100 Pavia, Italy), A. Piazza (Istituto di Genetica Medica, Università di Torino, 10100 Torino, Italy), and K. K. Kidd (Department of Human Genetics, School of Medicine, Yale University, New Haven, Connecticut 06510 U.S.A.) 1978. Testing of evolutionary independence in simulated phylogenetic trees. Syst. Zool. 27:391–400.—We can represent with a tree structure the dispersion matrix of a group of populations defined by a set of characters. The “treeness” test, T = c log R, where R is the ratio between the determinants of the observed and the estimated expected dispersion matrix and c is the number of characters, evaluates the validity of such a representation for a specific dispersion matrix. The test is based on a model of independent evolution: from an initial population a set of independent populations originates by successive splits. The treeness tends to a χ2 distribution, as the number of characters tends to infinity. We have analyzed the validity of the test: 1—with different ratios: (no. characters)/(no. populations); and 2—when conditions for independent evolution do not exist. These problems have been studied by designing two kinds of simulations. The first one generates trees through a process of independent evolution and the second one produces trees where a fraction of the final population results from the fusion of a pair of ancestor populations. In the first case we have studied 500 simulated trees with various levels of complexity. We have seen that the T distributions are actually consistent with χ2 distributions when the ratio (no. characters)/(no. populations) is greater than five. In the second case we have compared the distributions obtained from trees with independent populations and those obtained from trees with hybrid populations. In this case, even when the ratio (no. characters)/(no. populations) is high, the T distributions deviate very significantly from the χ2 distribution. Moreover, we have analyzed how much the time at which hybridization occurs affects the test for independent evolution. We have found that our test is relatively powerful in rejecting the hypothesis of independent evolution only when the hybridization takes place early enough, i.e., in the first half of the evolutionary time. The time intervals between two populations, estimated as the difference between the variances of the two populations, have been compared with those randomly determined by the simulation process. In the case of trees with independent populations the results confirm the expected value 1 and give evidence to the goodness of our estimation procedure; in the case of trees with hybrid populations the time intervals involved in the hybridization process are, as expected, significantly underestimated.