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The Lunar Laser Ranging (LLR) retroreflector arrays have been on the Moon for half a century. During that time, the laser range uncertainty has improved by a factor of 100. Consequently, the science results have also improved by orders of magnitude. New retroreflectors are scheduled to go to the Moon on Commercial Lander Payload Services missions and the Lunar Geophysical Network mission. The new retroreflectors are single 10 cm corner cube retroreflectors that will not spread the laser pulse during reflection like the existing arrays do. Due to the orbital and Earth rotational speeds, there is a velocity aberration of 0.″8–1.″5 for existing stations. Larger corner cubes require attention to ensure that the spread of possible velocity aberration displacements is optimally contained within the diffraction pattern. The diffraction pattern can be changed by making one or more of the rear dihedral angles slightly different from 90°. Improvements in the equipment at the LLR stations and improvements in the data analysis software are also desirable. Future possibilities are described.

Critical Art Encounters offer sustained and at times meditative engagements with contemporary artworks. This Critical Art Encounter is a kind of reprise, a return to a joint performance by visual artist Suné Woods, poet and theorist Fred Moten, and musician and theorist James Gordon Williams. Titled You are mine. I see now, I'm a have to let you go, the piece was performed live at the Hammer Museum during their 2018 biennial event “Made in L.A.” This special section of liquid blackness aims to sample the fully realized collaboration and audiovisual experimentation that took place in the largely improvised art event. This Critical Art Encounter includes the intimate ecological exploration that takes place in Woods's video work; Moten's poem “the general balm,” which was written in part for the performance and later published in his book of poetry and criticism all that beauty (2019); and finally, a conversation with Erin Christovale, an associate curator at the Hammer who helped organize the event. Although not all three artists are featured (Williams's original compositions can be heard in the footage from the performance), we were fortunate to expand this creative dialogue by including a curatorial perspective. Thus we are able to consider how this work expresses liquidity as both a concern of contemporary black art and a call to the congregation.

Rationale While nasal brushing transcriptomics can identify disease subtypes in chronic pulmonary diseases, it is unknown whether this is true in pediatric acute respiratory distress syndrome (PARDS). Objectives Determine whether nasal transcriptomics and methylomics can identify clinically meaningful PARDS subgroups that reflect important pathobiological processes. Methods Nasal brushings and serum were collected on days 1, 3, 7, and 14 from control and PARDS subjects from two centers. PARDS duration was the primary endpoint. Measurements and main results Twenty-four control and 39 PARDS subjects were enrolled. Two nasal methylation patterns were identified. Compared to Methyl Subgroup 1, Subgroup 2 had hypomethylation of inflammatory genes and was enriched for immunocompromised subjects. Four transcriptomic patterns were identified with temporal patterns indicating injury, repair, and regeneration. Over time, both inflammatory (Subgroup B) and cell injury (Subgroup D) patterns transitioned to repair (Subgroup A) and eventually homeostasis (Subgroup C). When control specimens were included, they were largely Subgroup C. In comparison with 17 serum biomarkers, the nasal transcriptome was more predictive of prolonged PARDS. Subjects with initial Transcriptomic Subgroup B or D assignment had median PARDS duration of 8 days compared to 2 in A or C (p = 0.02). For predicting PARDS duration ≥ 3 days, nasal transcriptomics was more sensitive and serum biomarkers more specific. Conclusions PARDS nasal transcriptome may reflect distal lung injury, repair, and regeneration. A combined nasal PCR and serum biomarker assay could be useful for predictive and diagnostic enrichment. Trial registration Clinicaltrials.gov NCT03539783 May 29, 2018.

Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows Earth's rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis. Here we integrate the Earth-Moon system backwards for 4.5Ga with orbital dynamics and explicit ocean tide models that are "high-level" (i.e., not idealized). To account for uncertain plate tectonic histories, we employ Monte Carlo simulations, with tidal energy dissipation rates (normalized relative to astronomical forcing parameters) randomly selected from ocean tide simulations with modern ocean basin geometry and with 55, 116, and 252Ma reconstructed basin paleogeometries. The normalized dissipation rates depend upon basin geometry and Earth's rotation rate. Faster Earth rotation generally yields lower normalized dissipation rates. The Monte Carlo results provide a spread of possible early values for the Earth-Moon system parameters. Of consequence for ocean circulation and climate, absolute (un-normalized) ocean tidal energy dissipation rates on the early Earth may have exceeded today's rate due to a closer Moon. Prior to ∼3Ga , evolution of inclination and eccentricity is dominated by tidal and core-mantle boundary dissipation within the Moon, which yield high lunar orbit inclinations in the early Earth-Moon system. A drawback for our results is that the semi-major axis does not collapse to near-zero values at 4.5Ga, as indicated by most lunar formation models. Additional processes, missing from our current efforts, are discussed as topics for future investigation.

Christian Scott aTunde Adjuah is an African American trumpeter, composer and producerfrom New Orleans, Louisiana. He has written compositions and performed improvisationscommitted to social justice themes. His cultural work is a natural extensionof his community service training directed by his grandfather Donald Harrison Sr. Hiscomposition 'Danziger' (2012) gives voice to the unarmed citizens injured and killed bypolice as they crossed the Danziger Bridge in the wake of Hurricane Katrina. 'Danziger'extends from his stretch music theory which aTunde Adjuah describes as disassemblingand reassembling musical ideas so that his compositions and improvisations canbe understood holistically. While aTunde Adjuah's interpretation of the Danziger Bridgeshootings is funneled through the ontological cornucopia of his trumpet and referenceshis particular community, the message he sends out through his custom-made trumpetbell is universal because his critique supports everyday human rights.

Differing environmental conditions can have profound effects on many behaviours in animals, especially where species have large geographic ranges. Seasonal changes or progression through life history stages impose differential constraints, leading to changes in behaviours. Furthermore, species which show flexibility in behaviours, may have a higher capacity to adapt to anthropogenic-induced changes to their environment. The red-throated diver (RTD) is an aquatic bird, that is able to forage in both freshwater and marine environments, though little else is known about its behaviours and its capacity to adapt to different environmental conditions. Here, we use time-depth recorders and saltwater immersion loggers to examine the foraging behaviour of RTDs from three regions across northwest Europe. We found that in the breeding season, birds from two regions (Iceland and Scotland) foraged in the marine environment, while birds from Finland, foraged predominantly in freshwater. Most of the differences in diving characteristics were at least partly explained by differences in foraging habitat. Additionally, while time spent foraging did not change through the breeding season, dives generally became more pelagic and less benthic over the season, suggesting RTDs either switched prey or followed vertical prey movements, rather than increasing foraging effort. There was a preference for foraging in daylight over crepuscular hours, with a stronger effect at two of the three sites. Overall, we provide the first investigation of RTD foraging and diving behaviour from multiple geographic regions and demonstrate variation in foraging strategies in this generalist aquatic predator, most likely due to differences in their local environment.

We utilize dissipatively coupled, time-multiplexed photonic resonator net-works to demonstrate topologically nontrivial behaviors in the dissipation of one- and two-dimensional lattices. We present edge state and band structure measurements of the these networks.

Quantum key distribution allows for a provably secure transmission of cryptographic keys over an optical channel. Encoded polarization states or time-bin degree of freedom have been used for successful demonstrations. However, photon losses in long fibers, slow single photon detectors, and detector dark counts significantly limit the overall bit rate. Improving key throughput and reducing the overhead of key reconciliation remain as major challenges. Methods which utilize multiple time bins allow for multiple key bits to be encoded in a single photon, thus increasing the fidelity of transmitted keys and decreasing the overhead of key reconciliation in real-world conditions. Previous implementations of these methods required that Alice and Bob share a time reference by sharing a dedicated classical channel used for synchronization. This work presents a technique that allows two parties to exchange time-bin encoded photons without the need for synchronized time references. Our technique uses a framing protocol which allows Alice to encode a time reference along with a key which is determined by Alice before transmission. Security can be achieved by monitoring the visibility of a pair of Franson interferometers, using decoy pulses and measuring the round trip time between Alice and Bob. The bit rate of this technique is limited only by the recovery time of the detector and the speed of the modulation electronics. We experimentally demonstrate a raw bit rate of 5Mb/s over an optical channel with 55dB of loss, which is competitive with current research. We also demonstrate absolute timing synchronization with an accuracy of 20ps.

Five retroreflector arrays currently on the Moon reflect short laser pulses back to Earth, allowing range to be measured. Each array has multiple small corner cubes. Due to variable lunar optical librations of the direction to Earth, the tilted arrays spread return times of single photons in the returned laser pulse, degrading the synthesized multiphoton normal point range accuracy. The Next Generation Lunar Retroreflectors (NGLRs) and MoonLIGHT reflectors currently being fabricated are larger 10 cm single corner cubes that do not spread the pulse. The Lunar Geophysical Network (LGN) mission will place NGLRs at three separated sites on the lunar nearside. The Commercial Lander Payload Service (CLPS) and early Artemis missions will precede the LGN mission. Solutions that include 6 yr of simulated Lunar Laser Ranging (LLR) data to two sites in the north and two in the south show improvement in the uncertainties of many science parameters. Lunar solution parameters include displacement Love numbers h 2 and l 2, tidal dissipation at several frequencies, fluid-core/solid-mantle boundary (CMB) dissipation, and moment of inertia combinations (C–A)/B and (B–A)/C, with principal moments of inertia A < B < C. Submeter-accuracy coordinates of the new reflectors will result from the first month of well-distributed data. There are benefits other than lunar science: gravitational physics includes the equivalence principle; Earth science includes terrestrial tidal dissipation and ranging station positions and motions; and astronomical constants with GM(Earth+Moon) for the gravitational constant times the mass of the Earth–Moon system. Improvements are illustrated for h 2, l 2, (C–A)/B, (B–A)/C, equivalence principle, and GM(Earth+Moon).

The Lunar Laser Ranging (LLR) experiment has accumulated 50 years of range data of improving accuracy from ground stations to the laser retroreflector arrays (LRAs) on the lunar surface. The upcoming decade offers several opportunities to break new ground in data precision through the deployment of the next generation of single corner-cube lunar retroreflectors and active laser transponders. This is likely to expand the LLR station network. Lunar dynamical models and analysis tools have the potential to improve and fully exploit the long temporal baseline and precision allowed by millimetric LLR data. Some of the model limitations are outlined for future efforts. Differential observation techniques will help mitigate some of the primary limiting factors and reach unprecedented accuracy. Such observations and techniques may enable the detection of several subtle signatures required to understand the dynamics of the Earth-Moon system and the deep lunar interior. LLR model improvements would impact multi-disciplinary fields that include lunar and planetary science, Earth science, fundamental physics, celestial mechanics and ephemerides., 8 pages, 1 figure, A white paper submitted to the Committee on the Planetary Science Decadal Survey (2023-2032) of The National Academies of Sciences

In this study, we investigate the machining behaviour of a Piperidine and a MDA cured DGEBA epoxy resin under low speed orthogonal micro-cutting conditions. The characteristics of chip-workpiece separation, chip formation and machined surface damage were examined in association with thermomechanical and mechanical properties of the epoxies. It is found that the separation of the chip from the workpiece takes place by fracture, according to Williams' model of machining. Further, cube-square scaling principles can be used to explain the mechanism of the observed brittle-to- ductile cutting behaviour of the epoxies. The results also show that the chip formation process is determined by both shear yielding and plastic bending behaviour of the material. In particular, chip formation involves the imposition of large strain plastic deformation. This explains the dependence of the cutting states (such as continuous chip and broken chip) on the degree of crosslink density of the epoxy, since the latter controls the post-yield deformability of epoxy chips. Based on our new findings, a modified Williams' cutting model is proposed to account for the chip formation behaviour of polymers in cutting.

Prince’s unparalleled, innovative musical style remains widely revered by his worldwide audience in the wake of his death less than two years ago. Since the late twentieth century, many scholars have used European critical theory to examine Prince’s musical multidimensionality. These important analyses help us understand Prince’s music and performativity in new ways but repeatedly ignore the cultural roots of his music. Indeed, many critical discussions focus on his performance of ambiguous sexualities and sartorial strategies without addressing how Prince’s understanding of his Blackness played a crucial role in his creative practice and theatricality. I contend that exploring Prince’s dynamic oeuvre through interpretive lenses of radical black theory is a productive space for understanding his performance of lyrical and musical liminality, his self-determination in the music business, and his commitment to using his music for racial uplift. Prince’s creative practices were linked to his covert, but avid, support of social justice initiatives that support black humanity. Framing my analysis through Prince’s composition “Black Muse” from his final studio album, I explain how “Black Muse” provides lyrical and musical evidence of Prince’s political thought and deployment of counter narratives. I put “Black Muse” in conversation with “Baltimore,” “Resolution,” and “Planet Earth,” unapologetically activist songs written by Prince that discuss police brutality, warmongering, and climate change. I discuss how Prince’s strategic use of musical liminality in “Lady Cabdriver” obscures his political diatribes through a layer of sonic salacity. Combining close musical analysis with Black theoretical thought that explores Prince’s definitions of Black Muse, I explore Prince’s performances of blues hybridity, his tireless effort in repositioning his relationship with the music industry, and his mission to uplift his people. While Prince had muses, who were both Black and white, Prince’s ultimate creative muse was the Black community and the black experience itself. Prince scholars can benefit from exploring and utilizing various black performance theories to better understand and explain his contribution to global music culture.

Only a few sites on Earth are technically equipped to carry out Lunar Laser Ranging (LLR) to retroreflector arrays on the surface of the Moon. Despite the weak signal, they have successfully provided LLR range data for about 49 years, generating about 26,000 normal points. Recent system upgrades and new observatories have made millimeter-level range accuracy achievable. Based on appropriate modeling and sophisticated data analysis, LLR is able to determine many parameters associated with Earth–Moon dynamics, involving the lunar ephemeris, lunar physics, the Moon’s interior, reference frames and Earth orientation parameters. LLR has also become one of the strongest tools for testing Einstein’s theory of general relativity in the solar system. By extending the standard solution, it is possible to solve for parameters related to gravitational physics, like the temporal variation of the gravitational constant, metric parameters as well as the strong equivalence principle, preferred-frame effects and standard-model extensions. This paper provides a review about LLR measurement and analysis. After a short historical overview, we describe the key findings of LLR, the apparatus and technologies involved, the requisite modeling techniques, some recent results and future prospects on all fronts. We expect continued improvements in LLR, maintaining its lead in contributing to science.

Understanding the rich social lives of animals benefits international conservation efforts. Postprint

The planetary and lunar ephemerides called DE440 and DE441 have been generated by fitting numerically integrated orbits to ground-based and space-based observations. Compared to the previous general-purpose ephemerides DE430, seven years of new data have been added to compute DE440 and DE441, with improved dynamical models and data calibration. The orbit of Jupiter has improved substantially by fitting to the Juno radio range and Very Long Baseline Array (VLBA) data of the Juno spacecraft. The orbit of Saturn has been improved by radio range and VLBA data of the Cassini spacecraft, with improved estimation of the spacecraft orbit. The orbit of Pluto has been improved from use of stellar occultation data reduced against the Gaia star catalog. The ephemerides DE440 and DE441 are fit to the same data set, but DE441 assumes no damping between the lunar liquid core and the solid mantle, which avoids a divergence when integrated backward in time. Therefore, DE441 is less accurate than DE440 for the current century, but covers a much longer duration of years −13,200 to +17,191, compared to DE440 covering years 1550–2650.

In the present paper, we investigate the material removal behaviour of epoxy-based composites in an orthogonal cutting process, and its dependence on two different fillers: a rigid nanosilica (SiO2) and a soft carboxyl-terminated butadiene-acrylonitrile (CTBN) elastomer. The results obtained show that fracture plays a key role in the formation of the newly cut surface as the chip is separated from the workpiece by the cutting tool. The surface finish after cutting is dependent on the cutting depth, h, and the ratio between fracture toughness and yield strength, Gc/σy. The latter can be determined by a cutting theory. In general, a smaller value of h and/or a higher value of Gc/σy favour the controllability of the surface finish, i.e., a stable material removal process with enhanced surface integrity. This work highlights the important role of the fillers in determining not only the mechanical properties of epoxy composites but also their machinability. It provides useful guidance for better design and processing of epoxy-based materials for different engineering applications. Keywords: Cutting, Material removal, Nanosilica and CTBN reinforced epoxy, Fracture, Surface finish

International audience; The interior structure of the Moon is constrained by its mass, moment of inertia, and k 2 and h 2 tidal Love numbers. We infer the likely radius, density, and (elastic limit) rigidity of all interior layers by solving the inverse problem using these observational constraints assuming spherical symmetry. Our results do not favor the presence of a low rigidity transition layer between a liquid outer core and mantle. If a transition layer exists, its rigidity is constrained to 43 +26 −9 GPa, with a preference for the high rigidity values. Therefore, if a transition layer exists, it is more likely to have a rigidity similar to that of the mantle (∼70 GPa). The total (solid and liquid) core mass fraction relative to the lunar mass is constrained to 0.0098 +0.0066 −0.0094 and 0.0198 +0.0026 −0.0049 for interior structures with and without a transition layer, respectively, narrowing the range of possible giant impact formation scenarios.

Small tidal forces in the Earth–Moon system cause detectable changes in the orbit. Tidal energy dissipation causes secular rates in the lunar mean motion n, semimajor axis a, and eccentricity e. Terrestrial dissipation causes most of the tidal change in n and a, but lunar dissipation decreases eccentricity rate. Terrestrial tidal dissipation also slows the rotation of the Earth and increases obliquity. A tidal acceleration model is used for integration of the lunar orbit. Analysis of lunar laser ranging (LLR) data provides two or three terrestrial and two lunar dissipation parameters. Additional parameters come from geophysical knowledge of terrestrial tides. When those parameters are converted to secular rates for orbit elements, one obtains dn/dt = $$-25.97\pm 0.05 ''/$$ cent $$^{2}$$ , da/dt = 38.30 ± 0.08 mm/year, and di/dt = −0.5 ± 0.1 $$\upmu $$ as/year. Solving for two terrestrial time delays and an extra de/dt from unspecified causes gives $$\sim $$ $$3\times 10^{-12}$$ /year for the latter; solving for three LLR tidal time delays without the extra de/dt gives a larger phase lag of the N2 tide so that total de/dt = $$(1.50 \pm 0.10)\times 10^{-11}$$ /year. For total dn/dt, there is $$\le $$ 1 % difference between geophysical models of average tidal dissipation in oceans and solid Earth and LLR results, and most of that difference comes from diurnal tides. The geophysical model predicts that tidal deceleration of Earth rotation is $$-1316 ''$$ /cent $$^{2}$$ or 87.5 s/cent $$^{2}$$ for UT1-AT, a 2.395 ms/cent increase in the length of day, and an obliquity rate of 9 $$\upmu $$ as/year. For evolution during past times of slow recession, the eccentricity rate can be negative.

As the number of purchases over the Internet has increased and the method of payment is a credit or debit card, e-commerce merchants must be able to accept on-line payment using the card data. Cyber-criminals have found ways to capture the information on credit and debit cards and use this information to make purchases and remove money from bank accounts which costs merchants lost revenue and chargebacks fees and cost consumers and banks lost funds.. The process by which credit and debit card payments are processed beginning with the e-commerce merchant's web site to a card processor or service gateway to the credit or debit card company's network to the issuing bank's network with an accept or decline response being returned to the merchant's shopping cart system via the same networks is discussed. The issue of credit and debit card fraud in terms of how cyber-criminals function and the solutions used to deter these attempts by the cyber-criminals is covered. The security standards and a list of preventive measures that should be used by e-commerce merchants are discussed.

The analysis of range or Doppler data between sites on the Earth and Moon requires an accurate computation of the lunar orbit and detailed models of the orientation of the Earth and Moon. Models constructed to understand range and range rate can lack detail, but if they include the largest lunar orbit variations, tracking stations on a rotating Earth, and lunar sites on a synchronously rotating Moon, then they will display the largest effects for orbit elements, Earth orientation, tracking station locations, and lunar site coordinates. The range and range rate are expanded into periodic series. To understand accurate solutions, the largest periodic terms that are sensitive to various solution parameters indicate the sensitivity of data to solution parameters and the time spans needed for their determination. Conclusions include: cylindrical coordinates work well for sites on the rapidly rotating Earth, but Cartesian coordinates are more natural for the synchronously rotating Moon since the series for the three coordinate projections are distinct. For range and range rate data, daily, semimonthly, monthly, and longer periods are present. For Doppler data, the daily periods may be stronger and more useful than the long periods, particularly for terms associated with the terrestrial tracking station. Doppler data do not determine the lander coordinate toward the Earth well. Observational strategies for range and Doppler data are not identical. For all data types, one wishes a variety of hour angles, lunar declinations, times of month, and longer periods. A long span of high-quality range data can improve the lunar orbit, orientation of the Earth’s equator, and physical librations. The locations of new lunar sites or new tracking stations can be determined from shorter spans of data.

BACKGROUND Many states, including Arkansas, require CPR training before high school graduation. METHODS We modified the American Heart Association's CPR in Schools curriculum to deliver CPR and AED training with maximal individual practice. RESULTS 520 students were trained over a two-day period at Little Rock Central High School. Three students were unable to effectively participate due to physical limitations. The model was later applied at the five other district public high schools. CONCLUSIONS Training large numbers of students in a time-compressed formal is feasible with a highly dedicated, practiced instructor team. This model may be applicable to workplace settings.

The present paper describes an investigation into the effects on the fatigue behaviour of adding up to 1.00 vol.% ZnO nano-rods with a diameter of 13 nm and an aspect ratio of three to two amorphous styrene acrylonitrile copolymers. Two acrylonitrile contents, i.e. 24% and 34% respectively, were studied. Fracture mechanics based fatigue tests were conducted at 5 Hz and a Paris Law analysis approach was followed. The fatigue threshold increased notably with the addition of the ZnO nano-rods. The increases in toughness were analysed using an analytical model of plastic void growth around the particles and this enabled the surface energy per unit area for the particle-matrix debonding process to be deduced. Good particle distributions were achieved only for very small volume fractions (

Cutting analyses incorporating chip bending in addition to shear yielding and fracture toughness have been presented. A plastic bending term (eb/γ)(hc/h) is included which corrects the yield stress, σY, determined from the cutting data. The experimental data for seven polymers derived from measuring both the chip thickness and the residual radius of curvature show that the contribution of bending is up to about 12%. This gives a correction to σY of about the same order but Gc is unaffected as (eb/γ)(hc/h) is a factor independent of the cutting depth. The corrected σY values are compared with the σY values in simple compression and it suggests a work hardening effect for the polyolefines. Also, the low bending strain in the chips of HMWPE and PP may be attributed their large degree of non-linearity observed in the compression test.

An investigation is made into the fracture properties of polymer films and laminates under cutting by a sharp tool and lateral tension under pure shear conditions. The method involves use of a sharp razor blade applied to the crack tip of polymer films which are also stretched orthogonal to the direction of the blade. The reaction force is measured as the cutting tool cuts the material and the force from applying a lateral strain is measured. The analysis and tests assume quasi-static conditions. The method is applied to a polyester film and three polyester laminates. Steady-state cutting forces are observed from cutting tests and loads at crack initiation are observed from lateral stretching tests. With fracture mechanics analysis the energy contributions from cutting and tearing are used to determine apparent fracture properties from the experimental results. It is observed that the cutting and tearing tests yield similar fracture toughness properties for the three tested polyester laminates, despite the different crack tip geometry at the point of crack growth. However, significantly larger fracture toughness values are measured from tearing tests versus cutting tests for the tested polyester film.

The prediction of failure loads in notched samples has been one of the most motivating fracture mechanics issues for a long time. Most efforts have been focused on the application of theoretical models with much less care in the experiments themselves. In this work the fracture of notched samples in epoxy resin is addressed from experimental and theoretical approaches. A set of fracture experiments has been carried out with a wide range of notch tip radii. Special care has been taken to ensure the accuracy of the notch geometry. Experiments have been compared with numerical predictions using the cohesive zone model and local fracture criteria based on the Theory of Critical Distances.

A review is given of describing the fracture of soft solids using the notion of energy release rate as proposed by Griffith. Soft solids have low modulus and, sometimes, low yield stresses which result in self-blunting when cracked specimens are loaded laterally. The resulting blunt cracks bring into play the requirement that some critical stress must be achieved as well as the energy release rate. This two criteria analysis is explored and conditions for sharp crack failure, blunt crack failure with elevated apparent toughness and ductile tearing when the critical stress is not achieved are described.

The fracture toughness, Gc, of three commercial polymers (HDPE, PP and PEEK) has been determined using a cutting test method. The traditional linear elastic fracture mechanics tests were conducted for comparison. The results showed that the cutting analysis is capable of giving valid fracture data for ductile polymers. However, when the cut depth is small, e.g. less than 100 μm, an inverse size effect on Gc was observed in cutting, i.e. the measured toughness of the polymers tends to decrease with the decrease of the cutting depth. Possible mechanisms for such a scale effect on fracture energy are discussed.

Two amorphous SAN copolymers with acrylonitrile contents of 24% and 34% have been modified by the incorporation of ZnO nano-particles at volume fractions of up to 2.00%. For the SAN with 24% acrylonitrile content, three types of nano-particles were added. The first two were cylindrical (nano-rods) and the third were spherical. For the SAN with 34% acrylonitrile content, just one of the cylindrical nano-particle types were used. The dispersion of the nano-particles was assessed using atomic force microscopy and agglomeration was observed for the higher volume fractions. Young’s modulus and fracture toughness values were measured for each system as a function of volume fraction. The smaller nano-rods were found to be the most effective for both stiffening and toughening the polymers and the spherical particles were found not to contribute to stiffness due to poor particle–matrix adhesion. At room temperature the maximum toughening contributions for all particles occurred at volume fractions of about 0.1%, above which a reduction was observed. At 80 °C the toughening contributions continued to rise slowly past 0.1% volume fraction. The toughening is consistent with the notion that the particles debond from the matrix and then plastic hole growth around the detached particles is initiated. The peak toughening observed at 0.1% volume fractions are the result of agglomeration occurring at higher volume fractions.

The mechanical behaviour of gelatine gels as a function of test rate and gelatine concentration was determined through lubricated uniaxial compression and wire cutting tests. Similar to other reported literature, it was observed that the fracture stress and strain of the gels were strongly strain rate dependent whereas the strain rate effect was insignificant on the deformation/stiffness properties. The wire cutting tests led to values of energy release rate, Gc, being determined as a function of cutting rate. It was found that at small rates (up to 10 mm/min), the value of Gc for the 10% w/w gelatine concentration was constant at an approximate value of 1.1 J/m 2 . For higher values of test rate, Gc increased such that the log Gc versus log cutting rate data were well approximated with a line of slope equal to 0.5. An analytical model describing this behaviour is suggested which takes into account the fluid flow of the water through the polymeric porous gel structure. In addition, a numerical simulation of the uniaxial compression was performed using a poroelastic material model. The model enabled the effect of the strain rate on the stress in the solid network and the pore pressure to be determined. A failure criterion based on maximum solid stress was suggested which led to a reasonable agreement with the experimental failure stress and strain data as a function of strain rate. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license

Solid body tides on the Moon vary by about ±0.1 m each month. In addition to changes in shape, the Moon's gravity field and orientation in space are affected by tides. The tidal expressions for an elastic sphere are compact, but dissipation introduces modifications that depend on the forcing period. Consequently, a Fourier representation of the tide-raising potential is needed. A mathematical model for the distortion-caused tidal potential may be used for the analysis of precise spacecraft tracking data. Since tides affect gravitational torques on the Moon from the Earth's attraction, the lunar orientation is also affected. Expressions for five periodic perturbations of orientation are presented. The rheological properties of lunar materials determine how the Moon responds to different tidal periods. New lunar laser ranging solutions for the tidal orientation terms are presented. The quality factor Q is 38 ± 4 at 1 month, 41 ± 9 at 1 year, ≥74 at 3 years, and ≥58 at 6 years. The ranging results can be matched with absorption band models that peak at ~120 days and single relaxation time models that peak at ~100 days. Combined models are possibilities. Dissipation can modify laser ranging solutions; previously reported core flattening is too uncertain to be useful. Strong lunar tidal dissipation, modeled to arise in the deep hot mantle, appears to be from a region with radius ≥535 km. Classical Maxwell-type dissipation is too weak to detect at 3 and 6 year periods.

More than 25 years ago we developed a data visualization system called Vibe. During this same period we developed a system for collaborative authoring – CASCADE – that made heavy use of visualization. These were but a few of many efforts at that time to develop new methods for understanding data, stimulated by improved hardware - faster CPUs, more memory and high resolution graphical displays that made it possible to perform advanced visualization on ordinary PCs. In this paper we revisit some of these efforts and then discuss where visualization is today. We briefly examine big data and scientific visualization where many of the issues we explored 25 years ago are being revisited. Our focus however is on general visualization. What we find is that advanced visualization systems for data presentations have not come into general use. We explore some of the reasons this may be the case.

The elastic analysis for a blunt crack is used together with the fracture criteria of a critical energy release rate and a cohesive stress. The notion of this stress occurring at some distance from crack tip is explored and bounds for possible fracture behaviour are derived. The upper bound seems to model fracture in ceramics and polymers and is very similar in form to cohesive zone results for a linear traction curve. This small strain elastic solution is extended to include self-blunting from the deformation. It is shown that it gives a sensible description of the behaviour of rubber and it is used to model the cutting of a stretched sheet.

A review will be given of the analysis of mixed mode delamination failure in composites and adhesive joints. There will be discussion of the issue of mode II failure and how it occurs only in laminates. In homogenous material mixed mode loading results in local mode I failure by the crack kinking. If the crack is constrained in its path, as in laminates, then an apparent mode II failure occurs consisting of a series of local mode I micro cracks. This has a rough surface and, in mode II (shear) does not open leading to an increased surface area and friction. This apparent mode II fracture, and its mixed mode variants, gives higher toughness values than in mode I. Measuring these mixed mode toughness values presents significant experimental problems but standard protocols have been developed to give reliable values and hence failure loci for mixed mode failure. It is a feature of such data that any mode II components gives significant scatter so there is inherent uncertainty present. The prediction of the mode mix in any configuration also presents significant problems. For elastic failures without damage there is a established solution arising from the stress singularities at the crack tip and effects of this are usually present when there is damage. However prediction of the mode mix depends on the form of the damage and is load level dependent. There are approximate ways of determining this mode mix which will be described but numerical calculations are often needed With this background in mind the practical value, in terms of refining design methods, by using such analyses will be discussed.

22.01.15 KB. Ok to add accepted version to spiral, subject to 12 months embargo which has expired - published online 12 Dec 2013

The Gravity Recovery and Interior Laboratory (GRAIL) mission has sampled lunar gravity with unprecedented accuracy and resolution. The lunar GM, the product of the gravitational constant G and the mass M, is very well determined. However, uncertainties in the mass and mean density, 3345.56 ± 0.40 kg/m3, are limited by the accuracy of G. Values of the spherical harmonic degree-2 gravity coefficients J2 and C22, as well as the Love number k2 describing lunar degree-2 elastic response to tidal forces, come from two independent analyses of the 3 month GRAIL Primary Mission data at the Jet Propulsion Laboratory and the Goddard Space Flight Center. The two k2 determinations, with uncertainties of ~1%, differ by 1%; the average value is 0.02416 ± 0.00022 at a 1 month period with reference radius R = 1738 km. Lunar laser ranging (LLR) data analysis determines (C − A)/B and (B − A)/C, where A

The resolution and accuracy of the lunar spherical harmonic gravity field have been dramatically improved as a result of the Gravity Recovery and Interior Laboratory (GRAIL) mission. From the Primary Mission, previous harmonic gravity fields resulted in an average n = 420 surface resolution and a Bouguer spectrum to n = 330. The GRAIL Extended Mission improves the resolution due to a lower average 23 km altitude orbit. As a result, new harmonic degree 900 gravity fields (GL0900C and GL0900D) show nearly a factor of 2 improvement with an average surface resolution n = 870 and the Bouguer spectrum extended to n = 550. Since the minimum spacecraft altitude varies spatially between 3 km and 23 km, the surface resolution is variable from near n = 680 for the central farside to near n = 900 for the polar regions. These gravity fields with 0.8 million parameters are by far the highest-degree fields of any planet ever estimated with a fully dynamic least squares technique using spacecraft tracking data.

In the USA, the national cyberinfrastructure refers to a system of research supercomputer and other IT facilities and the high speed networks that connect them. These resources have been heavily leveraged by scientists in disciplines such as high energy physics, astronomy, and climatology, but until recently they have been little used by biomedical researchers. We suggest that many of the ‘Big Data’ challenges facing the medical informatics community can be efficiently handled using national-scale cyberinfrastructure. Resources such as the Extreme Science and Discovery Environment, the Open Science Grid, and Internet2 provide economical and proven infrastructures for Big Data challenges, but these resources can be difficult to approach. Specialized web portals, support centers, and virtual organizations can be constructed on these resources to meet defined computational challenges, specifically for genomics. We provide examples of how this has been done in basic biology as an illustration for the biomedical informatics community.