Small-scale fluctuations of laser beam fluence at the large B-integral in ultra-high intensity lasers.

Analytical expressions for the spatial spectrum of fluence fluctuations of a laser pulse propagating in a medium with Kerr nonlinearity have been obtained. It is shown that inhomogeneities with a spatial scale much larger than the critical scale of self-focusing grow insignificantly even at large values of the B-integral. Experiments using BK7 glass and a KDP crystal as a nonlinear medium confirm the obtained theoretical results. This may be interesting for pulse post-compression, frequency doubling, and other experiments using transmission optical elements in ultra-high intensity lasers.

Improving focusability of post-compressed PW laser pulses using a deformable mirror.

The use of the post-compression technique ensures gain in laser pulse peak power but at the same time degrades beam focusability due to the nonlinear wavefront distortions caused by a spatially nonuniform beam profile. In this paper a substantial focusability improvement of a post-compressed laser pulse by means of adaptive optics was demonstrated experimentally. The Strehl ratio increase from 0.16 to 0.43 was measured. Simulations showed that the peak intensity in this case reaches 0.52 of the theoretical limit.

Compact pulse shaper based on a tilted volume Bragg grating.

A compact optical layout of a pulse shaper for strongly chirped laser pulses of nanosecond time scale exploiting a tilted chirped volume Bragg grating and a programmable spatial light modulator is proposed. The setup has a non-zero frequency dispersion; thus it may be used for stretching or compressing the pulse and controlling its shape simultaneously. The feasibility of spectral shaping with a resolution of 0.16 nm, corresponding to a time resolution of 150 ps, and a contrast ratio of 102 is demonstrated experimentally.

11 fs, 1.5 PW laser with nonlinear pulse compression.

The PEARL laser output pulse with a duration of 60-70 fs was compressed to 11 fs after passing through a 5-mm thick silica plate and reflecting from two chirping mirrors with a total dispersion of -250 fs2. The experiments were carried out for the B-integral values up to 19 without damage of the optical elements, which indicates that small-scale self-focusing was suppressed. The results obtained show the possibility of further nonlinear compression scaling to multipetawatt power in pulses with duration commensurate with the field period.

New feather mites of the Nycteridocaulus generic group (Acariformes: Proctophyllodidae) from passerines (Passeriformes) in Panama.

Three new feather mite species of the Nycteridocaulus generic group (Proctophyllodidae: Proctophyllodinae) are described from passerines in Panama: Atrichophyllodes myrmotherulae sp. n. from the Slaty Antwren, Myrmotherula schisticolor (Lawrence) (Thamnophilidae), Nycteridocaulus apanaskevichi sp. n. from the Grey-breasted Wood Wren, Henicorhina leucophrys (Tschudi) (Troglodytidae), and N. empidonicus sp. n. from the Yellowish Flycatcher Empidonax flavescens Lawrence (Tyrannidae). Nycteridocaulus apanaskevichi, presenting the second record of the genus from a host of oscine passerines, differs from N. guaratubensis Hernandes, 2014 in having the anterolateral extensions of the prodorsal shield rounded and the hysteronotal shield lacking any ornamentation. Males of N. empidonicus differ from N. myiobius Mironov, 2017 in having the supranal concavity open posteriorly and tarsus IV with rounded apical process; and females are distinguished by macrosetae h2 having long filiform apices. Males of A. myrmotherulae most clearly differ from A. mentalis Hernandes et al. 2007 in having the terminal lamellae rectangular and tarsus IV with triangular ventral process, and females are distinguished in having a noticeably longer idiosoma, 400-430 µm long. Comments on systematics and host associations of the genera Atrichophyllodes and Nycteridocaulus are provided.

Short-wave infrared light imaging measures tissue moisture and distinguishes superficial from deep burns.

Existing clinical approaches and tools to measure burn tissue destruction are limited resulting in misdiagnosis of injury depth in over 40% of cases. Thus, our objective in this study was to characterize the ability of short-wave infrared (SWIR) imaging to detect moisture levels as a surrogate for tissue viability with resolution to differentiate between burns of various depths. To accomplish our aim, we constructed an imaging system consisting of a broad-band Tungsten light source; 1,200-, 1,650-, 1,940-, and 2,250-nm wavelength filters; and a specialized SWIR camera. We initially used agar slabs to provide a baseline spectrum for SWIR light imaging and demonstrated the differential absorbance at the multiple wavelengths, with 1,940 nm being the highest absorbed wavelength. These spectral bands were then demonstrated to detect levels of moisture in inorganic and in vivo mice models. The multiwavelength SWIR imaging approach was used to diagnose depth of burns using an in vivo porcine burn model. Healthy and injured skin regions were imaged 72 hours after short (20 seconds) and long (60 seconds) burn application, and biopsies were extracted from those regions for histologic analysis. Burn depth analysis based on collagen coagulation histology confirmed the formation of superficial and deep burns. SWIR multispectral reflectance imaging showed enhanced intensity levels in long burned regions, which correlated with histology and distinguished between superficial and deep burns. This SWIR imaging method represents a novel, real-time method to objectively distinguishing superficial from deep burns.

Unexpected bird-feather mite associations revealed by DNA metabarcoding uncovers a dynamic ecoevolutionary scenario.

The high relevance of host-switching for the diversification of highly host-specific symbionts (i.e., those commonly inhabiting a single host species) demands a better understanding of host-switching dynamics at an ecological scale. Here, we used DNA metabarcoding to study feather mites on passerine birds in Spain, sequencing mtDNA (COI) for 25,540 individual mites (representing 64 species) from 1,130 birds (representing 71 species). Surprisingly, 1,228 (4.8%) mites from 84 (7.4%) birds were found on host species that were not the expected to be a host according to a recent bird-feather mite associations catalog. Unexpected associations were widespread across studied mite (40.6%) and bird (43.7%) species and showed smaller average infrapopulation sizes than typical associations. Unexpected mite species colonized hosts being distantly related to the set of their usual hosts, but with similar body size. The network of bird-mite associations was modular (i.e., some groups of bird and mite species tended to be more associated with each other than with the others), with 75.9% of the unexpected associations appearing within the module of the typical hosts of the mite species. Lastly, 68.4% of mite species found on unexpected hosts showed signatures of genetic differentiation, and we found evidence for reproduction or the potential for it in many of the unexpected associations. Results show host colonization as a common phenomenon even for these putatively highly host-specific symbionts. Thus, host-switching by feather mites, rather than a rare phenomenon, appears as a relatively frequent phenomenon shaped by ecological filters such as host morphology and is revealed as a fundamental component for a dynamic coevolutionary and codiversification scenario.

Causality analysis of leading singular value decomposition modes identifies rotor as the dominant driving normal mode in fibrillation.

Cardiac fibrillation is a major clinical and societal burden. Rotors may drive fibrillation in many cases, but their role and patterns are often masked by complex propagation. We used Singular Value Decomposition (SVD), which ranks patterns of activation hierarchically, together with Wiener-Granger causality analysis (WGCA), which analyses direction of information among observations, to investigate the role of rotors in cardiac fibrillation. We hypothesized that combining SVD analysis with WGCA should reveal whether rotor activity is the dominant driving force of fibrillation even in cases of high complexity. Optical mapping experiments were conducted in neonatal rat cardiomyocyte monolayers (diameter, 35 mm), which were genetically modified to overexpress the delayed rectifier K+ channel IKr only in one half of the monolayer. Such monolayers have been shown previously to sustain fast rotors confined to the IKr overexpressing half and driving fibrillatory-like activity in the other half. SVD analysis of the optical mapping movies revealed a hierarchical pattern in which the primary modes corresponded to rotor activity in the IKr overexpressing region and the secondary modes corresponded to fibrillatory activity elsewhere. We then applied WGCA to evaluate the directionality of influence between modes in the entire monolayer using clear and noisy movies of activity. We demonstrated that the rotor modes influence the secondary fibrillatory modes, but influence was detected also in the opposite direction. To more specifically delineate the role of the rotor in fibrillation, we decomposed separately the respective SVD modes of the rotor and fibrillatory domains. In this case, WGCA yielded more information from the rotor to the fibrillatory domains than in the opposite direction. In conclusion, SVD analysis reveals that rotors can be the dominant modes of an experimental model of fibrillation. Wiener-Granger causality on modes of the rotor domains confirms their preferential driving influence on fibrillatory modes.

Enabling large-scale feather mite studies: an Illumina DNA metabarcoding pipeline.

Feather mites are among the most common and diverse ectosymbionts of birds, yet basic questions such as the nature of their relationship remain largely unanswered. One reason for feather mites being understudied is that their morphological identification is often virtually impossible when using female or young individuals. Even for adult male specimens this task is tedious and requires advanced taxonomic expertise, thus hampering large-scale studies. In addition, molecular-based methods are challenging because the low DNA amounts usually obtained from these tiny mites do not reach the levels required for high-throughput sequencing. This work aims to overcome these issues by using a DNA metabarcoding approach to accurately identify and quantify the feather mite species present in a sample. DNA metabarcoding is a widely used molecular technique that takes advantage of high-throughput sequencing methodologies to assign the taxonomic identity to all the organisms present in a complex sample (i.e., a sample made up of multiple specimens that are hard or impossible to individualise). We present a high-throughput method for feather mite identification using a fragment of the COI gene as marker and Illumina Miseq technology. We tested this method by performing two experiments plus a field test over a total of 11,861 individual mites (5360 of which were also morphologically identified). In the first experiment, we tested the probability of detecting a single feather mite in a heterogeneous pool of non-conspecific individuals. In the second experiment, we made 2 × 2 combinations of species and studied the relationship between the proportion of individuals of a given species in a sample and the proportion of sequences retrieved to test whether DNA metabarcoding can reliably quantify the relative abundance of mites in a sample. Here we also tested the efficacy of degenerate primers (i.e., a mixture of similar primers that differ in one or several bases that are designed to increase the chance of annealing) and investigated the relationship between the number of mismatches and PCR success. Finally, we applied our DNA metabarcoding pipeline to a total of 6501 unidentified and unsorted feather mite individuals sampled from 380 European passerine birds belonging to 10 bird species (field test). Our results show that this proposed pipeline is suitable for correct identification and quantitative estimation of the relative abundance of feather mite species in complex samples, especially when dealing with a moderate number (> 30) of individuals per sample.

Constitutive Intracellular Na+ Excess in Purkinje Cells Promotes Arrhythmogenesis at Lower Levels of Stress Than Ventricular Myocytes From Mice With Catecholaminergic Polymorphic Ventricular Tachycardia.

BACKGROUND: In catecholaminergic polymorphic ventricular tachycardia (CPVT), cardiac Purkinje cells (PCs) appear more susceptible to Ca(2+) dysfunction than ventricular myocytes (VMs). The underlying mechanisms remain unknown. Using a CPVT mouse (RyR2(R4496C+/Cx40eGFP)), we tested whether PC intracellular Ca(2+) ([Ca(2+)]i) dysregulation results from a constitutive [Na(+)]i surplus relative to VMs. METHODS AND RESULTS: Simultaneous optical mapping of voltage and [Ca(2+)]i in CPVT hearts showed that spontaneous Ca(2+) release preceded pacing-induced triggered activity at subendocardial PCs. On simultaneous current-clamp and Ca(2+) imaging, early and delayed afterdepolarizations trailed spontaneous Ca(2+) release and were more frequent in CPVT PCs than CPVT VMs. As a result of increased activity of mutant ryanodine receptor type 2 channels, sarcoplasmic reticulum Ca(2+) load, measured by caffeine-induced Ca(2+) transients, was lower in CPVT VMs and PCs than respective controls, and sarcoplasmic reticulum fractional release was greater in both CPVT PCs and VMs than respective controls. [Na(+)]i was higher in both control and CPVT PCs than VMs, whereas the density of the Na(+)/Ca(2+) exchanger current was not different between PCs and VMs. Computer simulations using a PC model predicted that the elevated [Na(+)]i of PCs promoted delayed afterdepolarizations, which were always preceded by spontaneous Ca(2+) release events from hyperactive ryanodine receptor type 2 channels. Increasing [Na(+)]i monotonically increased delayed afterdepolarization frequency. Confocal imaging experiments showed that postpacing Ca(2+) spark frequency was highest in intact CPVT PCs, but such differences were reversed on saponin-induced membrane permeabilization, indicating that differences in [Na(+)]i played a central role. CONCLUSIONS: In CPVT mice, the constitutive [Na(+)]i excess of PCs promotes triggered activity and arrhythmogenesis at lower levels of stress than VMs.

Convergent and unidirectional evolution of extremely long aedeagi in the largest feather mite genus, Proctophyllodes (Acari: Proctophyllodidae): Evidence from comparative molecular and morphological phylogenetics.

Proctophyllodid feather mites (400+ species) are permanent (full-time) symbionts commonly occurring on passerine birds. Phenotypic evolution of these mites appears to be greatly influenced by characters related to reproduction (>87.5% of a total of 32 taxonomically important discrete characters) and male genitalic characters (21.9%). Because sexual selection could the major evolutionary driver in this system, we test the theoretical expectation that genitalic or sexually dimorphic characters should evolve more rapidly and divergently then other characters. We inferred a time-calibrated molecular phylogeny (6 genes, 8571 nt aligned, no missing data) for 133 taxa of proctophyllodid mites and 40 outgroups. Comparisons of the average number of character state changes inferred on 10,696 Bayesian stationary trees indicate that male genitalic or sexually dimorphic characters do not evolve significantly faster than other characters (p=0.537 and p=0.819, respectively). However, among the male genitalic characters, a trait related to the relative length of the aedeagus experienced extremely fast rates of evolution and was detected as a statistical outlier. In this character, the transitions between short, long, and several intermediate states occurred in both directions. In contrast, the evolution of extremely long aedeagi (nearly as long as the body) occurred unidirectionally and irreversibly. This surprising result may be due to constraints imposed by the female spermathecal canal, which, in species where males have extremely long aedeagi, is also very long and may impede pumping sperm by short aedeagi. In proctophyllodid mites, extremely long aedeagi evolved independently five times in five different monophyletic lineages. Several of these lineages were lumped together by taxonomists to form easy-to-distinguish but apparently artificial species-groups. Male genitalic characters, thus, can introduce false synapomorphies that could affect morphology-based phylogenetic inference. For the most species-rich genus, Proctophyllodes, we develop a predictive classification of species-groups that reconciles molecular and morphological data.

Cophylogenetic analyses reveal extensive host-shift speciation in a highly specialized and host-specific symbiont system.

Host-shift speciation and cospeciation are the two major processes driving symbiont macroevolutionary diversification. Cospeciation is expected to be frequent in vertically transmitted and host-specific symbionts, and leads to congruent host-symbiont phylogenies. However, the cophylogenetic dynamics of many groups of highly specialized host-specific symbionts is largely unstudied. Thus, the relevance of cospeciation vs. host-shift speciation remains largely unknown. Here, we investigated this question by performing the largest cophylogenetic study of feather mites to date, using both distance and event-based cophylogenetic methods. For these analyses, we inferred phylogenies based on all protein coding genes of the mitochondrial genome of Proctophyllodes and Trouessartia feather mite species living on European passerine birds. Results show high incongruence among bird and feather mite phylogenies, because of extensive host-switching. We conclude that host-shift speciation, rather than cospeciation, may be the main driver of symbiont diversification even for highly specialized symbionts with low host-switching potential.

Two new feather mites of the genus Proctophyllodes Robin, 1868 (Acari: Proctophyllodidae) from European passerines (Aves: Passeriformes).

Two new species of the feather mite genus Proctophyllodes Robin, 1868 (Analgoidea: Proctophyllodidae) are described from two passerine birds (Passeriformes) in Europe: Proctophyllodes markovetsi n. sp. from the tawny pipit Anthus campestris (L.) (Motacillidae) and P. loxiae n. sp. from the red crossbill Loxia curvirostra (L.) (Fringillidae). Males of P. markovetsi are most clearly distinguished from the closely related P. tchagrae Atyeo & Braasch, 1966 by having greater terminal lamellae (30-40 × 20-25 µm), the tips of genital arch curved medially, and the corolla of the anal sucker with 14-15 denticles; females of this species are characterised by the terminal appendages distinctly longer than the lobar region width. Males of P. loxiae differ from the closest species, P. fuchsi Mironov, 1997, by having smaller terminal lamellae (45-50 × 22-28 µm), the genital organ extending beyond the posterior margin of lamellae by half their length; females can be distinguished by having the terminal cleft noticeably wider than long (28-30 × 35-40 µm).

Deficient cMyBP-C protein expression during cardiomyocyte differentiation underlies human hypertrophic cardiomyopathy cellular phenotypes in disease specific human ES cell derived cardiomyocytes.

AIMS: Mutations of cardiac sarcomere genes have been identified to cause HCM, but the molecular mechanisms that lead to cardiomyocyte hypertrophy and risk for sudden death are uncertain. The aim of this study was to examine HCM disease mechanisms at play during cardiac differentiation of human HCM specific pluripotent stem cells. METHODS AND RESULTS: We generated a human embryonic stem cell (hESC) line carrying a naturally occurring mutation of MYPBC3 (c.2905 +1 G >A) to study HCM pathogenesis during cardiac differentiation. HCM-specific hESC-derived cardiomyocytes (hESC-CMs) displayed hallmark aspects of HCM including sarcomere disarray, hypertrophy and impaired calcium impulse propagation. HCM hESC-CMs presented a transient haploinsufficiency of cMyBP-C during cardiomyocyte differentiation, but by day 30 post-differentiation cMyBP-C levels were similar to control hESC-CMs. Gene transfer of full-length MYBPC3 during differentiation prevented hypertrophy, sarcomere disarray and improved calcium impulse propagation in HCM hESC-CMs. CONCLUSION(S): These findings point to the critical role of MYBPC3 during sarcomere assembly in cardiac myocyte differentiation and suggest developmental influences of MYBPC3 truncating mutations on the mature hypertrophic phenotype.

Global associations between birds and vane-dwelling feather mites.

Understanding host-symbiont networks is a major question in evolutionary ecology. Birds host a great diversity of endo- and ectosymbiotic organisms, with feather mites (Arachnida: Acariformes: Analgoidea, Pterolichoidea) being among the most diverse of avian symbionts. A global approach to the ecology and evolution of bird-feather-mite associations has been hampered because of the absence of a centralized data repository. Here we present the most extensive data set of associations between feather mites and birds. Data include 12 036 records of 1887 feather mite species located on the flight feathers of 2234 bird species from 147 countries. Feather mites typically located inside quills, on the skin, or on downy body feathers are not included. Data were extracted from 493 published sources dating from 1882 to 2015. Data exploration shows that although most continents and bird families are represented, most bird species remain unexplored for feather mites. Nevertheless, this is the most comprehensive data set available for enabling global macroecological analyses of feather mites and their hosts, such as ecological network analyses. This metadata file outlines the structure of these data and provides primary references for all records used.

A new feather mite of the genus Pteronyssoides Hull, 1931 (Astigmata: Pteronyssidae) from thrushes (Passeriformes: Turdidae) in the New World.

A new feather mite species, Pteronyssoides turdinus n. sp. (Acariformes: Pteronyssidae), is described from two species of thrushes, Turdus amaurochalinus Cabanis (type-host) and T. leucomelas Vieillot (Passeriformes: Turdidae) in Minas Gerais, Brazil. The new species belongs to the parinus species group and most clearly differs from previously known species of this group by the following features: in both sexes of P. turdinus, setae c2 are anterior to the level of the sejugal furrow; in males, the anterior margin of the hysteronotal shield has a deep trapezoidal concavity, setae d1 are situated on the striated tegument, the adanal shield is represented by a narrow longitudinal sclerite, and tarsus and tibia of legs IV are subequal in length; in females, the opisthosomal sclerites are split into proper opisthosomal sclerites and pygidial fragments encompassing the bases of setae h2 and h3. This is the first description of a feather mite of the genus Pteronyssoides Hull, 1931 from birds of the family Turdidae.

A new feather mite of the genus Dolichodectes (Astigmata: Proctophyllodidae) from Hippolais polyglotta (Passeriformes: Acrocephalidae) in Spain.

A new feather mite species, Dolichodectes hispanicus sp. n. (Astigmata: Proctophyllodidae), is described from the Melodious Warbler Hippolais polyglotta (Vieillot) (Passeriformes: Acrocephalidae) in Spain. The new species is closest to the type species of the genus, D. edwardsi (Trouessart, 1885) from the Grear Reed-Warbler Acrocephalus arundinaceus (Linnaeus) (Acrocephalidae). Adults of D. hispanicus differ from those of D. edwardsi by dimensional characteristics, in particular, by having shorter aedeagus that does not extend to the anal suckers in males and shorter hysteronotal shield in females. Tritonymphs of D. hispanicus are much more distinctive and differ from those of D. edwardsi by having the prodorsal shield covering all the prodorsum, the hysteronotal shield occupying about three quarters of the hysterosoma, and idiosomal setae h3 being filiform. The morphological description of the new species is augmented by sequence data from the mitochondrial cytochrome c oxidase subunit I gene fragment (COI).

New species of the feather mite genus Promegninia Gaud & Atyeo (Acari: Avenzoariidae) from petrels and shearwaters (Procellariiformes: Procellariidae).

Two new species of the feather mite genus Promegninia Gaud & Atyeo, 1967 (Avenzoariidae: Bonnetellinae) are described from procellariids in the northeasterm Atlantic Ocean: Promegninia bulweriae n. sp. from the Bulwer's petrel Bulweria bulwerii (Jardine & Selby) and P. calonectris n. sp. from the Cory's shearwater Calonectris borealis (Cory) (Procellariiformes: Procellariidae). Males of P bulweriae n. sp. are most clearly distinguished from the other known species in the genus by having short legs III extending only to the level of lobar apices and short conical tarsi III with lanceolate ventral seta w; females of this species are characterised by the absence of additional sclerites at postero-lateral angles of the prodorsal shield. Males of P. calonectris differ from the other known species in having bidentate terminal lamellae on the lobar apices and the entire adanal shield; females of this species are distinguished by having well-developed pygidial shields and a hysteronotal shield encompassing the bases of setae c2. Sequence data of the mitochondrial cytochrome c oxidase subunit I gene fragment (COI) are also obtained for the new species. An updated diagnosis of Promegninia and a key to the known species are provided.

Reduced Na⁺ current density underlies impaired propagation in the diabetic rabbit ventricle.

Diabetes is associated with an increased risk of sudden cardiac death, but the underlying mechanisms remain unclear. Our goal was to investigate changes occurring in the action potential duration (APD) and conduction velocity (CV) in the diabetic rabbit ventricle, and delineate the principal ionic determinants. A rabbit model of alloxan-induced diabetes was utilized. Optical imaging was used to record electrical activity in isolated Langendorff-perfused hearts in normo-, hypo- and hyper-kalemia ([K(+)]o=4, 2, 12 mM respectively). Patch clamp experiments were conducted to record Na(+) current (I(Na)) in isolated ventricular myocytes. The mRNA/protein expression levels for Nav1.5 (the α-subunit of I(Na)) and connexin-43 (Cx43), as well as fibrosis levels were examined. Computer simulations were performed to interpret experimental data. We found that the APD was not different, but the CV was significantly reduced in diabetic hearts in normo-, hypo-, and, hyper-kalemic conditions (13%, 17% and 33% reduction in diabetic vs. control, respectively). The cell capacitance (Cm) was increased (by ~14%), and the density of INa was reduced by ~32% in diabetic compared to control hearts, but the other biophysical properties of I(Na) were unaltered. The mRNA/protein expression levels for Cx43 were unaltered. For Nav1.5, the mRNA expression was not changed, and though the protein level tended to be less in diabetic hearts, this reduction was not statistically significant. Staining showed no difference in fibrosis levels between the control and diabetic ventricles. Computer simulations showed that the reduced magnitude of I(Na) was a key determinant of impaired propagation in the diabetic ventricle, which may have important implications for arrhythmogenesis.

New species of the feather mite family Proctophyllodidae (Acariformes: Astigmata) from two species of mockingbirds (Passeriformes: Mimidae) in eastern North America.

Four new species of the feather mite family Proctophyllodidae are described from two species of the family Mimidae (Passeriformes): Proctophyllodes apanaskevichi sp. n. (Proctophyllodinae) and Amerodectes dumetellae sp. n. (Pterodectinae) from the Gray Catbird, Dumetella carolinensis (L., 1766), and Proctophyllodes gallowayi sp. n. (Proctophyllodinae) and Metapterodectes toxostomae sp. n. (Pterodectinae) from the Brown Thrasher, Toxostoma rufum (L., 1758). A. dumetellae and M. toxostomae represent the first records of mites of the subfamily Pterodectinae on mockingbirds.