Experimental Branches Research Articles

Estimation of viscoelastic properties in ribbon-shaped homogeneous waveguides by wavenumber analysis and model reduction

Wavenumber based procedures applied to 1D waveguides provide a rigorous framework with an exact signal model that allows for a proper identification of both storage and loss properties independently from the boundary conditions. However, the associated inverse problem is either computationally intense if using a reference solution (e.g. SAFE) or limited to a specific frequency range that depends on the reduced beam model. We propose here to apply the wavenumber-based estimation of isotropic viscoelastic properties to ribbon-shaped homogeneous waveguides, characterized by a rectangular section with slender height-to-width aspect ratio. We show theoretically that considering the ribbon as a thick plate by assuming a model reduction in the height dimension, drastically reduces the wave propagation problem (hence its inverse counterpart) while providing a sufficiently good approximation on the low height-to-wavelength regime. In addition, full-field measurements are performed on an Aluminium and a PVC homogeneous ribbon-shaped waveguide. The experimental dispersive branches (bending and torsion modes) are identified on an ultra-wide frequency range (1 kHz - 1 MHz) using High Resolution Wave Analysis. For both materials, an excellent agreement is observed with the thick plate reduced model, paving the way for wide-band viscoelastic properties identification of ribbon-shaped waveguide.

Optical autocollimator for vibration measurements at Diamond I13 beamline

I13 is a 250 m long hard X-ray beamline for imaging and coherence experiments at the Diamond Light Source [1]. The beamline comprises two independent experimental branches: one for imaging in direct space using X-ray microscopy and one for imaging in reciprocal space using coherent imaging techniques. The mechanical stability is very important for implementation of increased capabilities at latest generation of long beamlines [2]. Therefore, the beam stability monitoring is essential part of the day-to-day operation of the beamlines as well as for analysis of mechanical instability sources for the Diamond II upgrade. In this paper we present the setup developed to measure mechanical stability of beamline based on optical autocollimator.

Golden Standard or Obsolete Method? Review of ECG Applications in Clinical and Experimental Context.

Cardiovascular system and its functions under both physiological and pathophysiological conditions have been studied for centuries. One of the most important steps in the cardiovascular research was the possibility to record cardiac electrical activity. Since then, numerous modifications and improvements have been introduced; however, an electrocardiogram still represents a golden standard in this field. This paper overviews possibilities of ECG recordings in research and clinical practice, deals with advantages and disadvantages of various approaches, and summarizes possibilities of advanced data analysis. Special emphasis is given to state-of-the-art deep learning techniques intensely expanded in a wide range of clinical applications and offering promising prospects in experimental branches. Since, according to the World Health Organization, cardiovascular diseases are the main cause of death worldwide, studying electrical activity of the heart is still of high importance for both experimental and clinical cardiology.

Investigation of a four-bladed propeller inflow at yaw

An investigation has been conducted which looks to understand the effect of yaw on the inflow of a 4-bladed propeller. Both experimental and numerical work has been conducted, with the test data used to validate and compare against the numerical methods. The numerical methods involve fully resolved CFD and the low-order Crigler method. Comparing at a yaw angle of 15°, good agreement is found between the numerical and experimental results with adjustments made to account for discrepancies between the setups. More work is still required in the experimental and numerical branches to improve the extraction of data with minimal losses and improve the fidelity of simpler methods without a great expansion of computer cost.

Two methods to study inelastic neutron-scattering measurements based on ω n (q) versus S(q, ω) applied to the magnetic open honeycomb lattice Tb2Ir3Ga9

This work describes two methods to fit the inelastic neutron-scattering spectrum S(q, ω) with wavevector q and frequency ω. The common and well-established method extracts the experimental spin-wave branches ω n (q) from the measured spectra S(q, ω) and then minimizes the difference between the observed and predicted frequencies. When n branches of frequencies are predicted but the measured frequencies overlap to produce only m < n branches, the weighted average of the predicted frequencies must be compared to the observed frequencies. A penalty is then exacted when the width of the predicted frequencies exceeds the width of the observed frequencies. The second method directly compares the measured and predicted intensities S(q, ω) over a grid {q i , ω j } in wavevector and frequency space. After subtracting background noise from the observed intensities, the theoretical intensities are scaled by a simple wavevector-dependent function that reflects the instrumental resolution. The advantages and disadvantages of each approach are demonstrated by studying the open honeycomb material Tb2Ir3Ga9.

“How Much Is Not Enough?”: Public Library Outreach to “Disadvantaged” Communities in the War on Poverty

This article explores the class politics of urban public librarianship through “outreach” efforts during the federal War on Poverty, using the Chicago Public Library as a case study. Using federal money available through the Library Services and Construction Act of 1964, major metropolitan library systems spent nearly a decade opening experimental branches in “disadvantaged” Black and Latinx neighborhoods and publicizing library services to “the urban poor.” Although urban public library outreach was nothing new, this effort reflected the influence of both the civil rights movement and the short-lived national attempt to eradicate poverty, and it unearthed the same conflicts. Outreach efforts allowed activists, staff, and “disadvantaged” communities to challenge public libraries’ authoritarianism, but devastating budget cuts in a slowing economy put public libraries on the defensive in the latter half of the 1970s, leaving political conflicts in librarianship and the nation’s cities to smolder as the War on Poverty was gradually abandoned.

Phyllanthus emblica L. (amla) branch: A safe and effective ingredient against skin aging

Background and aimSkin aging influences the changes in skin, including skin dryness, wrinkle, and irregular pigmentation. Amla (Phyllanthus emblica L.) branch has shown several benefits, but not the anti-skin aging. The study aimed to evaluate the anti-skin aging efficacy of amla branch. Experimental procedureAmla branches were standardized the phenolic acids. The extract was investigated anti-skin aging activities, including antioxidant, anti-tyrosinase, anti-melanogenesis, and matrix metalloproteinase-2 inhibitory assays. Topical gel containing extract was prepared and evaluated the skin irritation by a single closed patch test. Randomized, double-blind, placebo-control study was performed in 20 volunteers for 84 consecutive days. The tested skin was evaluated by Chromameter® CR 400, Dermalab® USB, Mexameter® MX 18, Corneometer® CM 825, and Visioscan® VC 98. ResultsAmla branch extract, a dark brown powder, consisted a variety of phenolic acids, mainly sinapic and ferulic acids. The extract exhibited the potent antioxidant and tyrosinase inhibitory activities in vitro assays and the melanin suppression through inhibition of tyrosinase and tyrosinase-related protein-2 activities, the strong antioxidant, and the potent matrix metalloproteinase-2 in cellular assays at 0.1 mg/mL. Topical gel containing 0.1% extract was a stable and safe formulation. Clinical study was proved the superior anti-skin aging efficacy, including the lightening skin color, the enhanced skin elasticity and hydration, and the skin wrinkle reduction. ConclusionThe study results suggested that amla branch is a rich source of bioactive compounds and can be a potential ingredient for utilization in anti-skin aging products.

Mapping research fields using co-nomination: the case of hyper-authorship heavy flavour physics

This paper introduces the use of co-nomination as a method to map research fields by directly accessing their knowledge networks organised around exchange relationships of intellectual influence. Co-nomination is a reputation-based approach combining snowball sampling and social network analysis. It compliments established bibliometric mapping methods by addressing some of their typical shortcomings in specific instances. Here we test co-nomination by mapping one such instance: the idiosyncratic field of CERN-based heavy flavour physics (HFP). HFP is a ‘hyper-authorship’ field where papers conventionally list thousands of authors alphabetically, masking individual intellectual contributions. We also undertook an illustrative author co-citation analysis (ACA) mapping of 2310 HFP articles published 2013–18 and identified using a simple keyword query. Both maps were presented to two HFP scientists for commentary upon structure and validity. Our results suggest co-nomination allows us to access individual-level intellectual influence and discern the experimental and theoretical HFP branches. Co-nomination is powerful in uncovering current and emerging research specialisms in HFP that might remain opaque to other methods. ACA, however, better captures HFP’s historical and intellectual foundations. We conclude by discussing possible future uses of co-nomination in science policy and research evaluation arrangements.

Simulation and prediction of optical characterization of casting (Adamantan-Fulgide) thin films using (CTANNs) approach

For reinforcement, the photochromic field and the cooperation between the theoretical and experimental branches of physics, the computational, theoretical artificial neural networks (CTANNs) and the resilient back propagation (R[Formula: see text]) training algorithm were used to model optical characterizations of casting (Admantan-Fulgide) thin films with different concentrations. The simulated values of ANN are in good agreement with the experimental data. The model was also used to predict values, which were not included in the training. The high precision of the model has been constructed. Moreover, the concentration dependence of both the energy gaps and Urbach’s tail were, also tested. The capability of the technique to simulate the experimental information with best accuracy and the foretelling of some concentrations which is not involved in the experimental data recommends it to dominate the modeling technique in casting (Admantan-Fulgide) thin films.

Spring bird migration as a dispersal mechanism for the hemlock woolly adelgid

In eastern North America, the invasive hemlock woolly adelgid (Adelges tsugae Annand), has expanded northward at a pace that exceeds predictions from mechanistic models, suggesting successful long-distance dispersal despite the only viable dispersive phase being a flightless nymph, or “crawler.” We hypothesize that migrating birds may contribute to long-distance dispersal of crawlers by passively transporting them in their plumage during northward migration. We collected hemlock woolly adelgid crawlers from the plumage of wild birds in Connecticut hemlock forests in spring and summer 2016–2017 and evaluated the factors that influence crawler loads on wild birds. Of 456 birds examined, 40 individuals of 22 species carried adelgid crawlers. Crawler loads varied strongly over time, showing a mid-spring peak that mirrored the phenological pattern in crawler abundance. However, crawler load was not affected by either local crawler abundance at capture sites or the degree of bird species association with hemlock forests. To test whether dispersed crawlers could start new invasions, we experimentally simulated avian-assisted dispersal of adelgids onto uninfested nursery hemlocks. Although rare, crawlers placed on birds did settle successfully on experimental branches during the adelgid’s summer generation. Our study confirms that birds carry hemlock woolly adelgid crawlers most often during the period of peak spring songbird migration, and that crawlers can move off bird plumage to settle on hemlock foliage. Bird-mediated, long-distance dispersal of crawlers likely has played a key role in hemlock woolly adelgid spread, and with warming temperatures, this mechanism may continue to be important for future range expansion.

Factors affecting morphological transformation and secondary attachment of apexes of Chondracanthus chamissoi (Rhodophyta, Gigartinales)

Fragments of Chondracanthus chamissoi have the capacity of secondary attachment. In the laboratory, apexes of upright branches of C. chamissoi placed 1–2 mm and parallel to horizontal substrata underwent morphological transformation prior to becoming attached, changing from thick and blunt to elongated and cylindrical and from straight to curved towards the substratum, where they eventually produced secondary attachment discs. When transformation occurred, signs could already be observed after 3 days of incubation. Several factors that could affect transformation and attachment were tested. The vertical or horizontal orientation of the fragments, the angle of incidence of light, and the phase of the life cycle had no effect on transformation, whereas the presence of reproductive structures had a negative effect compared to vegetative fragments. Low light intensity and low water flow favored the transformation response. Calcareous substrata (bivalve shells and coralline crusts) produced the highest frequency of transformation and other solid substrata (glass slides, rock, and sea-squirt tunic) followed in the ranking, but fleshy seaweeds (Ulva sp., Sarcothalia crispata, and C. chamissoi) failed to produce any response. Thus, the experimental upright branches developed features and reactivity similar to basal branches when the former were placed in conditions similar to those where the latter occur in the natural environment. Vegetative reproduction has been incorporated in cultivation techniques of C. chamissoi, but it could also be used in repopulation or restoration programs of this species.

AmpliconDuo: A Split-Sample Filtering Protocol for High-Throughput Amplicon Sequencing of Microbial Communities.

High throughput sequencing (HTSeq) of small ribosomal subunit amplicons has the potential for a comprehensive characterization of microbial community compositions, down to rare species. However, the error-prone nature of the multi-step experimental process requires that the resulting raw sequences are subjected to quality control procedures. These procedures often involve an abundance cutoff for rare sequences or clustering of sequences, both of which limit genetic resolution. Here we propose a simple experimental protocol that retains the high genetic resolution granted by HTSeq methods while effectively removing many low abundance sequences that are likely due to PCR and sequencing errors. According to this protocol, we split samples and submit both halves to independent PCR and sequencing runs. The resulting sequence data is graphically and quantitatively characterized by the discordance between the two experimental branches, allowing for a quick identification of problematic samples. Further, we discard sequences that are not found in both branches (“AmpliconDuo filter”). We show that the majority of sequences removed in this way, mostly low abundance but also some higher abundance sequences, show features expected from random modifications of true sequences as introduced by PCR and sequencing errors. On the other hand, the filter retains many low abundance sequences observed in both branches and thus provides a more reliable census of the rare biosphere. We find that the AmpliconDuo filter increases biological resolution as it increases apparent community similarity between biologically similar communities, while it does not affect apparent community similarities between biologically dissimilar communities. The filter does not distort overall apparent community compositions. Finally, we quantitatively explain the effect of the AmpliconDuo filter by a simple mathematical model.

Low-index nanopatterned barrier for hybrid oxide-free III-V silicon conductive bonding.

Oxide-free bonding of a III-V active stack emitting at 1300-1600 nm to a silicon-on-insulator wafer offers the capability to electrically inject lasers from the silicon side. However, a typical 500-nm-thick silicon layer notably attracts the fundamental guided mode of the silicon + III-V stack, a detrimental feature compared to established III-V Separate-Confinement Heterostructure (SCH) stacks. We experimentally probe with photoluminescence as an internal light source the guiding behavior for oxide-free bonding to a nanopatterned silicon wafer that acts as a low-index barrier. We use a sub-wavelength square array of small holes as an effective "low-index silicon" medium. It is weakly modulated along one dimension (superperiodic array) to outcouple the resulting guided modes to free space, where we use an angle-resolved spectroscopy study. Analysis of experimental branches confirms the capability to operate with a fundamental mode well localized in the III-V heterostructures.

Time-of-flight measurements at the Super-FRS

FAIR will deliver primary beam intensities of up to 5 × 1011 ions/s of 238U at energy of 1.5 GeV/u, which will make possible to produce secondary beams with a factor up to 10000 in intensity over present. Rare isotopes of all elements up to uranium will be produced via fission/fragmentation, spatially separated within a few hundred nanoseconds, and delivered to different experimental branches of the Super-FRS. For radioactive ion beams at velocities β = 0.8–0.9 a time-of-flight resolution below 50 ps is necessary in order to resolve mass number A ≈ 200. In order to face the present technical challenges, i.e. high intensity and high resolution, a solution based on diamond focal plane detectors is presently under investigation as timing detection system of the Super-FRS.

The Nobler Angels of Our Nature

The Nobler Angels of Our Nature

Capillary condensation in mesoporous silica with surface roughness

We construct an atomistic silica pore model mimicking templated mesoporous silica MCM-41, which has molecular-level surface roughness, with the aid of the electron density profile (EDP) of MCM-41 obtained from X-ray diffraction data. Then, we present the GCMC simulations of argon adsorption on our atomistic silica pore models for two different MCM-41 samples at 75, 80, and 87 K, and the results are compared with the experimental adsorption data. We demonstrate that accurate molecular modeling of the pore structure of MCM-41 by using the experimental EDP allows the prediction of experimental capillary evaporation pressures at all investigated temperatures. The experimental desorption branches of the two MCM-41 samples are in good agreement with equilibrium vapor–liquid transition pressures from the simulations, which suggests that the experimental desorption branch for the open-ended cylindrical pores is in thermodynamic equilibrium.

One hundred years of X-ray diffraction, 50 years of structural biology

Since the pioneering diffraction experiments led by Max von Laue in 1912, X-ray crystallography has progressed with a spectacular pace, opening research, and application perspectives in fields such as materials science, chemistry, mineralogy, environmental sciences, biotechnology and biomedicine. Such developments have been supported by discoveries in both the theoretical and experimental branches of science that granted the different communities access to specific investigation tools. In the biological field the highest challenge presented to X-ray crystallography has been linked to the study of proteins and nucleic acids, i.e., macromolecular structures composed of thousands of atoms, often available for the analyses in microscopic crystals of low intrinsic order. To support the development of macromolecular crystallography several complementary techniques had to be devised, such as methods in biochemistry and molecular biology, but also progresses in synchrotron X-ray sources. As the contemporary crystallographic methods allow facing very complex protein structures, in relatively short response times, the interest of corporate research for applied crystallography has grown substantially in the last two decades. In particular, current approaches to drug discovery and optimization rely on rational principles that stem from crystallographic investigations on protein/lead complexes, and on cyclic optimization of their chemical synthesis. Notably, the United Nations declared 2014 the International Year of Crystallography in consideration of the fundamental role played by crystallography for the growth of scientific knowledge.

Land‐use and edge effects unbalance seed dispersal and predation interactions under habitat fragmentation

AbstractThe process of fragmentation can greatly influence plant–animal interactions. To assess the degree to which it affects the balance between two interactions of opposite sign, namely seed dispersal and post‐dispersal seed predation, we selected 16 patches of chestnut forest in O Courel and El Bierzo, northwestern Spain. We assessed the effect of fragmentation over two different seed dispersal–predation systems using Helleborus foetidus and Ilex aquifolium as model species. In the first case, field experiments consisted of seed‐offering trays with selective exclusion of rodents and ants in a two‐way orthogonal design. In the second experiment, we placed experimental branches and trays on the floor to assess seed dispersal and predation. The interactions between several fragment traits and the relative contribution of rodents, ants and birds to seed removal were analyzed by means of generalized linear mixed models. Results show that for H. foetidus, differences in seed dispersal–predation were accounted for by patch shape, which affected mainly the dispersal phase. Major seed dispersal took place in patches with a smaller edge to core ratio and high plant cover (abandoned patches), whilst the latter also showed maximum seed predation. For I. aquifolium, fragmentation effects were significant only for seed predation, which was increased in abandoned patches. This shows that the effects of habitat fragmentation can emerge at different phases depending on specific traits of the interacting animals. It also highlights the importance of traditional land‐use practices in species interactions.

NUSTAR and the status of the R3B project at FAIR

Over the last 15 years, reaction experiments on fixed targets using secondary beams of high energy have developed a potential as exploratory tool to study the properties of nuclei far from stability. NUSTAR (nuclear structure, astrophysics and reactions) is a collaboration of the international nuclear structure and astrophysics community with the aim to further explore this method at the FAIR Facility. Within the FAIR complex, NUSTAR defines a facility where the heart is the super-fragment separator (Super-FRS), which serves three experimental branches: The RING, the LOW- and the HIGH-ENERGY branches.

Impact of plant architecture versus leaf quality on attack by leaf-tying caterpillars on five oak species

Because shelter-building herbivorous insect species often consider structural features of their host plants in selecting construction sites, their probability of attack is likely to be a function of some combination of plant architectural traits and leaf quality factors. We tested the hypothesis that plant architecture, in the form of the number of touching leaves, influences interspecific variation in attack by leaf-tying caterpillars in five species of sympatric Missouri oaks (Quercus). We compared colonization on control branches, in which both architecture and leaf quality were potentially important, with colonization on experimental branches for which we controlled for the effects of architecture by creating equal numbers of artificial ties. Colonization of artificial ties was highly correlated with natural colonization on neighboring control branches, suggesting that leaf quality factors and not architecture influenced interspecific variation in attack by leaf-tying caterpillars. Of the leaf quality factors measured (water, protein-binding capacity, nitrogen, specific leaf area, pubescence, and toughness), nitrogen was the most explanatory. With the exception of white oak, natural leaf tie colonization was positively correlated with nitrogen availability (ratio of nitrogen to protein-binding capacity), and negatively correlated with protein-binding capacity of leaf extracts. Both host plant species and subgenus oak influenced the community composition of leaf-tying caterpillars and the non-tying symbionts colonizing the ties. Host plant differences in leaf nitrogen content were positively correlated with pupal weight of one of two caterpillar species reared on all five host plant species. Thus, interspecific differences in nitrogen, nitrogen availability, and protein-binding capacity of leaf extracts are the best predictors at this time of interspecific differences in attack by leaf-tying caterpillars, in turn affecting their success on individual host plants in the laboratory.