Approximate Profile Maximum Likelihood

We propose an efficient algorithm for approximate computation of the profile maximum likelihood (PML), a variant of maximum likelihood maximizing the probability of observing a sufficient statistic rather than the empirical sample. The PML has appealing theoretical properties, but is difficult to compute exactly. Inspired by observations gleaned from exactly solvable cases, we look for an approximate PML solution, which, intuitively, clumps comparably frequent symbols into one symbol. This amounts to lower-bounding a certain matrix permanent by summing over a subgroup of the symmetric group rather than the whole group during the computation. We extensively experiment with the approximate solution, and find the empirical performance of our approach is competitive and sometimes significantly better than state-of-the-art performance for various estimation problems

Factors explaining variation in <i>C. humilis</i> seed predation in the Iberian Peninsula.

<p>a) Model-adjusted mean percent seed predation in each geographical region for human-altered and natural populations. b) Model-adjusted mean number of beetle holes for human-altered and natural populations. Error bars represent standard errors.</p

Hierarchical Levels of Seed Predation Variation by Introduced Beetles on an Endemic Mediterranean Palm

<div><p>Seed predators can limit plant recruitment and thus profoundly impinge the dynamics of plant populations, especially when diverse seed predators (e.g., native and introduced) attack particular plant populations. Surprisingly, however, we know little concerning the potential hierarchy of spatial scales (e.g., region, population, patch) and coupled ecological correlates governing variation in the overall impact that native and introduced seed predators have on plant populations. We investigated several spatial scales and ecological correlates of pre-dispersal seed predation by invasive borer beetles in <i>Chamaerops humilis</i> (Arecaceae), a charismatic endemic palm of the Mediteranean basin. To this end, we considered 13 palm populations (115 palms) within four geographical regions of the Iberian Peninsula. The observed interregional differences in percentages of seed predation by invasive beetles were not significant likely because of considerable variation among populations within regions. Among population variation in seed predation was largely related to level of human impact. In general, levels of seed predation were several folds higher in human-altered populations than in natural populations. Within populations, seed predation declined significantly with the increase in amount of persisting fruit pulp, which acted as a barrier against seed predators. Our results revealed that a native species (a palm) is affected by the introduction of related species because of the concurrent introduction of seed predators that feed on both the introduced and native palms. We also show how the impact of invasive seed predators on plants can vary across a hierarchy of levels ranging from variation among individuals within local populations to large scale regional divergences.</p></div

Main results of our generalized mixed linear models testing the effect of region (Valencia, Sevilla, Huelva, Cádiz-Malaga,), type of population (human-altered, natural) and amount of persisting fruit pulp on <i>C. humilis</i> seed predation and the average number of invertebrate holes per preyed seed.

<p>Significant differences (<i>P</i><0.05) are marked in bold.</p><p>Main results of our generalized mixed linear models testing the effect of region (Valencia, Sevilla, Huelva, Cádiz-Malaga,), type of population (human-altered, natural) and amount of persisting fruit pulp on <i>C. humilis</i> seed predation and the average number of invertebrate holes per preyed seed.</p

Summary table showing the number of <i>C. humilis</i> individuals and number of fruits sampled in each population, the habitat type, geographical region, type of population (i.e., human-altered [H] vs. natural [N]), and the percent predation and average number of holes per predated seed.

<p>Summary table showing the number of <i>C. humilis</i> individuals and number of fruits sampled in each population, the habitat type, geographical region, type of population (i.e., human-altered [H] vs. natural [N]), and the percent predation and average number of holes per predated seed.</p

Negative linear relationships between percentage of seed predation and amount of persisting fruit pulp in each of the four target regions.

<p>Negative linear relationships between percentage of seed predation and amount of persisting fruit pulp in each of the four target regions.</p

Foreign-body reaction of the different meshes.

<p>Immunohistochemical labelling of rabbit macrophages (arrows) using the RAM-11 monoclonal antibody (200x) (top panel). Positive cell percentages recorded after 14 and 90 days of implant (bottom panel). Results are expressed as the mean ± SEM. *, p<0.01 and #, p<0.001 vs. Ventralight^TM at 14 days; |, p<0.01 and †, p<0.001 vs. Ventralight^TM at 90 days; ‡, p<0.05 vs. Bard mesh^TM at 90 days. Prosthetic filaments (F), polyglecaprone film (*). Physiomesh^TM (Phy), new composite mesh (NCM), Ventralight^TM (VL).</p

Used biomaterials.

<p>Scanning electron microscopy images (100×) showing the aspect and the thickness of <i>Bio-A</i> (A), <i>Tuto</i> (B) and <i>St</i> (C). Polarized light images, with collagen fibers displayed in red after Sirius Red staining (200×). <i>Bio-A</i> (D), <i>Tuto</i> (E) and <i>St</i> (F).</p

Collagen 1 and 3 mRNA expression determined by RT-PCR.

<p>Stacked bar charts of the relative mRNA amounts, collagen 1 (white bar) and 3 (black bar), recorded for Bard mesh^TM (A), Physiomesh^TM (B), the new composite mesh (C) and Ventralight^TM (D) at the different study times (left panel). Results are the mean ± SEM of three experiments. Gene expression was normalized to that of the GAPDH gene. Agarose gels obtained (right panel). Mw: molecular weight markers; 1/2: 14 days postimplant; 3/4: 90 days postimplant; N: negative. Col 1: *, p<0.05 and **, p<0.01 vs. Bard^TM at 90 days; #, p<0.01 vs. new composite mesh at 14 days. Col 3: |, p<0.05 vs. Bard^TM at 90 days; †, p<0.05 and ††, p<0.01 vs. Physiomesh^TM at 14 days; ‡, p<0.05 vs. new composite mesh at 14 days.</p

Load (N)/Elongation (mm) curves of the different meshes.

<p>The Load/Elongation curves of all the different groups, at 90 days, were represented in the figure. From these curves the Young´s modulus of the different groups of our study were calculated and statistically analyzed. Bard mesh^TM (Bard), Physiomesh^TM (Phy), new composite mesh (NCM), Ventralight^TM (VL). </p