Search

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on September 26, 2022 as a planetary defense test. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defense, intended to validate kinetic impact as a means of asteroid deflection. Here we report the first determination of the momentum transferred to an asteroid by kinetic impact. Based on the change in the binary orbit period, we find an instantaneous reduction in Dimorphos's along-track orbital velocity component of 2.70 +/- 0.10 mm/s, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact. For a Dimorphos bulk density range of 1,500 to 3,300 kg/m$^3$, we find that the expected value of the momentum enhancement factor, $\beta$, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg/m$^3$, $\beta$= 3.61 +0.19/-0.25 (1 $\sigma$). These $\beta$ values indicate that significantly more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos., Comment: accepted by Nature

To prepare for two NASA missions, Southwest Research Institute has been performing both laboratory tests and hydrocode computations of impacts at velocities between 2 and 5.5 km/s on rocks like pumice, sandstone, hematite, concrete, and on metals like aluminum and pure iron (ARMCO iron). All the targets were mounted on pendulums so that the momentum imparted by the projectile to the target could be measured. Note that, in general, the momentum acquired by the target after the impact is larger than the momentum of the projectile. This is due to the additional momentum from the ejecta that flies off the target in the opposite direction to the direction of the impact. Hydrocode computations with CTH and EPIC followed the experiments. This paper will present the laboratory results specifically on ARMCO iron, a material considered a “benchmark”, and the strength and weaknesses of the computations performed.

When a high speed or hypervelocity impact occurs, a crater is formed. Size scaling of this event is of interest, meaning, for example, how the crater properties change as the projectile size increases. While penetration depth normalized by projectile radius is fairly insensitive to projectile size, there are other aspects of the cratering process that are quite sensitive to the size of the projectile, including mass of material liberated as ejecta and the amount of momentum that ejecta material has. It is show that there is reasonably good understanding of ejecta mass, but momentum enhancement is still a challenging topic, which we show through experimental results with two aluminums. We also discuss the same effects in concrete targets and the possibility of obtaining more understanding of the size scaling process with the upcoming DART impact into an asteroid.

An impact experiment was performed with a target of relevance to the upcoming DART impact. In this experiment, a collection of stones that is similar to a rubble pile was the target, though it was necessary to hold the stones in place (in this case with cement) since the target was hung vertically to perform the experiment. The stones–cement target has a higher density and a lower porosity than expected for Dimorphos, with the density being 2.92 g cm−3. A 3 cm diameter aluminum sphere was launched at a speed of 5.44 km s−1, which is similar to the anticipated 6.1 km s−1 impact speed of DART. The stones–concrete target was completely disassembled by the impact. The target was mounted on a pendulum. The swing of the pendulum was measured and from it the momentum enhancement β = 3.4 − 1.0 + 0.1 was measured. Due to possible lateral expansion of debris material, this value is a lower bound on the momentum enhancement that would be imparted to an extended target.

This graduate text is indispensable for those wanting to see and understand the mechanics of extreme dynamic events. It describes in detail the mechanics and material models used in understanding impact and penetration events. Covers continuum mechanics, the Hugoniot jump conditions, plasticity theory, damage and failure theory, shock and wave propagation in both Eulerian and Lagrangian frameworks, and the high pressure and high-rate response of materials. Nonlinearity in response of materials and systems is a common theme, showing itself in interesting and surprising ways. Materials are studied through damage to failure, since in armor and protection applications materials are utilized all the way through failure. Continuum and constitutive modelling topics required for modern large-scale numerical simulation techniques are clearly described. Extensive exercises ensure comprehension and explore new topics. This text is appropriate for a variety of graduate courses, including Continuum Mechanics, Advanced Solid Mechanics, and Plasticity and Inelasticity Theory.

Experiments were performed measuring mass liberated from an Al 2024-T351 target during impacts by a 3.0-cm-diameter aluminum sphere in the range of 4 to 5.77 km/s. The experiments were performed with a large two-stage light gas gun firing into targets mounted on a pendulum. The mass liberated from the targets, as measured by pre- and post-test weighing of the target, shows an interesting size-scale behavior when compared with historical data on Al 2024-T4 targets performed at smaller scale. Essentially, small spherical impactors (up to 1.27 cm in diameter) show a mass liberation that scales with impact speed times the square root of the diameter of the impactor. However, somewhere in the region of 1 cm diameter, the liberated mass transitions to scaling in terms of impact speed squared and there is no longer a size scale dependence on the liberated mass. This ejecta mass behavior is interpreted in the context of damage saturation. To support the analysis, computations were performed looking at damage model behavior that is required to support such a size scale transition in the region of 1 cm impactor diameter. Features of the computations are discussed, including sensitivity to initial conditions (because of the failure) and effects of the implementation in the Eulerian hydrocode CTH.

Methods for determining target resistance using velocity fields have been very successful for hemispherical-nosed and eroding projectiles which produce a hemispherical flow. Pointed-projectile-induced target flow fields are more challenging due to the pointed nose itself being a singular point in the flow. This paper develops a flow field, based on the curl of a vector potential, that produces a singular flow field for pointed projectiles (including ogives and cones) and produces target resistances through integrating plastic work rates over the flow field. To give an example of the utility of these new flow fields and target resistances, comparisons are made using the new flow field in the Walker-Anderson model for ogival-nosed APM2 projectile ballistic limits and deep penetration. Agreement is excellent.

Hypervelocity tests with aluminum spheres of 1 and 1.75 inch (2.54 and 4.45 cm)-diameter impacting pumice boulders at 2.1 km/s have been performed at Southwest Research Institute. The results and analysis of the impacts are the main objective of a companion paper, while this work focuses on finding the material properties of the pumice and the computer simulations of the impact. The pumice material was tested in compression both unconfined and confined. The crush-up curve was implemented in a foam model in CTH and in the Holmquist-Johnson concrete model in EPIC. Results of the simulations like depth of penetration, crater diameter, and momentum enhancement are compared with the tests. It is found that these simple models provide reasonable results for crater depth and diameter but more work needs to be performed to properly predict the momentum enhancement, i.e. the ejecta from the pumice target.

Momentum enhancement refers to the effect of more momentum being transferred to a target than resides in the impactor. This increased momentum transfer is due to crater ejecta leaving the impacted body in the direction opposite to the impactor travel direction. An application for this effect is using hypervelocity impactors to deflect potentially hazardous asteroids and comet nuclei. A concern with historical work with consolidated material is the effect of porosity in the impacted body on momentum enhancement. Hypervelocity impact tests were performed of aluminum spheres striking pumice boulders. The pumice boulders ranged in mass from 70 to 486 kg and had an estimated porosity of 70 – 75%. Two different projectiles diameters were used (2.54 cm and 4.45 cm) to study the effect of size scale. Impacts occurred at roughly 2.1 km/s. Depth of penetration was measured, an estimated crater radius was measured (though the crater geometries were irregular), and momentum enhancement was measured. Significant scatter was observed in the results even though the tests were carefully controlled, with measured momentum enhancements ranging from 1 to 1.69 and the average being β = 1.3.

Low Temperature Co-fired Ceramics (LTCC) represent a multilayer electronic packaging technology with the ability to incorporate many electrical components such as conductive, resistive, and dielectric materials, into a single monolithic package. Example devices would include capacitors, inductors, resistors, antennae, transformers, hybrid circuits, etc. In general, the LTCC package consists of a glass/ceramic dielectric and compatible conductive inks (Au, Ag, etc.). The dielectrics and conductors are patterned/laminated to form the desired 3D structure and then co-fired to complete densification. The resulting monolithic block is mechanically robust with a high density of (often buried) electrical components. Typically, LTCC systems have found implementation in circuitry utilizing the RF and microwave frequency ranges. In general, the material design and processing parameters, and knowledge of how these affect the final mechanical and electrical properties of the LTCC package are needed for successful circuit design. The electronic performance of an LTCC dielectric/conductor system (Ferro L8) was investigated as a function of processing parameters (peak fire temperature, temperature ramp rate, furnace air flow, etc.). Comparisons were also made between multiple manufacturing sites as the mentioned processing parameters vary slightly from site to site even with nominally identical set points due to differences in furnace design, fab layout, etc. Material properties of fired parts such as effective permittivity and electrical losses were measured both on bare dielectric using resonant cavity methods and on the dielectric/conductor system as a whole using microstrip transmission line methods to frequencies as high as 50 GHz. Correlations were made between electrical performance and models based on material properties. The effects of varied processing parameters and processing sites were also studied and used to help establish process understanding and improvement with respect to high frequency electrical performance. As an example, optimization of electrical performance could be achieved by adjusting the nominal furnace temperature set point at a specific site where losses were slightly high even with identical processing parameters to those at another manufacturing site.

Momentum enhancement occurs when impactors strike objects at hypervelocities due to the formation of crater ejecta whose departure from the impact body impart more momentum to the impacted body. In previous work the momentum enhancement caused when metals, rock, and pumice were impacted have been examined [1-7]. Momentum enhancement is quantified by β, which is the ratio of the resulting target momentum by the impactor momentum. By quantifying momentum enhancement it is possible to make informed decisions about the use of hypervelocity impactors to deflect celestial bodies such as asteroids or comet nuclei.

Reinforced carbon-carbon (RCC) composite is used in applications where structural stiffness and strength must be maintained at very high temperatures that may reach 2000°C or more. For example, it was used on both the Space Shuttle’s nose cone and the leading edges of its wings. As exemplified by the Space Shuttle Columbia accident, the ability of these materials to survive impacts up to hypervelocity speeds can be critical for some applications. As computational modeling becomes an increasingly important component of the design process, the ability to accurately model RCC materials under impact conditions likewise becomes more and more important. This paper describes a computational model of the thermal protection used on the Space Shuttle orbiter. The model incorporates both the RCC comprising much of the protection system and its silicon carbide coating. The model was subjected to hypervelocity impacts with both steel and aluminum projectiles, and the results were compared to test data from the literature.

Concrete, sandstone, and, in a previous round of experiments, pumice, were tested under hypervelocity impact at SwRI. Aluminum spheres with diameters of 1 and 1.75 in were shot at a velocity of approximately 2 km/s using a 50-mm conventional powder gun. The targets were mounted on a swing so that the momentum enhancement could be measured. The size effect, i.e. comparing momentum enhancement generated by the small and large projectiles, was of particular interest in this project. The targets were also scaled, although for sandstone we were limited by the natural geometry of the rocks. The results from the experiments show a clear size effect for the concrete while sandstone did not show any size effect, possibly because of experimental artifacts. The sandstone behavior was investigated with computations using the EPIC hydrocode. The porosity and compressive strength of the sandstone used in the impact tests were measured and reported. The rock is very similar to one reported and extensively tested by Lawrence Livermore Laboratory in 1974. Two material models (Holmquist-Johnson Concrete and Johnson-Holmquist-Beissel) were fit to the data from LLL. The momentum enhancement predicted by the code is reported for different parameter studies.

Two NASA missions that will be launched in 2022 have spun renewed interest in hypervelocity impact of rocks and metals. This work focuses on the prediction of the momentum enhancement effect, i.e. the extra momentum acquired by the target due to the ejecta flying off the target in the direction of the impactor. Predicting the momentum enhancement with simulations has been elusive, probably because the target material is rarely well characterized. This presentation shows that, given a good knowledge of the properties of the target material and, by adding two essential pieces of the physics (strength of failed material and bulking after failure), the computer simulations can provide good predictions of the momentum enhancement for hypervelocity impact tests performed at Southwest Research Institute.

The present work aims at presenting consistent data both from laboratory characterization and from blast tests to see how a computer model performs when only data from mechanical tests are being fed to the constitutive model. A sand (Ottawa 20-30) that meets ASTM C778 requirements, i.e., well characterized microscopically, was tested in triaxial compression under confinement pressures ranging from 50 to 300 MPa and moisture contents of 0 to 15% as well as high strain-rates. These tests provided both the experimental equation of state (pressure vs. volume) and compaction curves as well as the strength vs. pressure properties to build a constitutive model both in LS-DYNA and CTH. Blast tests were subsequently performed by burying explosive at three different depths inside a sand pot with a rigid steel plate on top. During flight, the height of the steel plate was tracked with Phantom high-speed cameras to determine the impulse transmitted to the plate as well as the maximum jump height. Simulations were performed with both an Eulerian code (CTH) and a Lagrangian/ALE code (LS-DYNA) using the constitutive model determined during the material characterization. The predictions of both codes are as close as 7% and as far as 22%, depending on the test configuration.

An LTCC tape dielectric (A6M) was fired stepwise from 775°C – 925°C using standard industry profiles. The fired tapes were investigated for shrinkage, density, crystallization (XRD), composition distribution (SEM/EDS), and high frequency (10 GHz) electrical properties. The tape consists of a glassy material that undergoes crystallization upon firing. Two crystalline phases were observed along with residual glass. Both crystallized phases appear to alter their unit cell dimensions with firing temperature. Fired tape density and XY-shrinkages were stable over the temperature range studied. Electrical properties (εr, tan δ) were stable above 825°C including and up to the maximum temperature studied.

Five nominally identical blast-loading tests were conducted where dynamic deflection data was collected. The dynamic deformation data collected was of the upper surface of a blastloaded hull shape. This data allowed the determination of the initial velocity imparted to each point of the surface in the first 1 or 2 milliseconds of the blast event. Analysis of this data showed that the spatial variation of the normalized blast loading is small, in particular it is less than 5%. Larger variations occur for the total blast impulse. Thus, the spatial distribution of the blast event (when normalized by the initial impulse) has less variation and is more repeatable than the actual total impulse of a blast event.

In the previous symposium, it was demonstrated that extrapolation of momentum enhancement β data from small laboratory tests to larger asteroid and comet nucleus deflection scenarios predicts large β values due to the fact that β does not scale with size. The big question in the extrapolation to larger scales is whether the damage process in the crater formation saturates at some scale – i.e., is there a size beyond which the momentum enhancement does scale, and thus the large scale large β values are not realized. In this work we take the data from the NASA Ames gun in the 1960s by Denardo and Nysmith [1] and examine its clear lack of scaling in more detail. We determine the behavior of the ejecta mass. We show that the amount of ejecta mass is proportional to the impact velocity squared times the square root of the projectile diameter, a quantity which has the dimensions of fracture toughness. Thus, it is likely that the mass liberation process depends on fracture toughness, which contrasts with the fact that the crater size depends on target material strength. Thus, a small fracture toughness leads to large ejecta mass, and that in turn leads to large momentum enhancement. The appearance of the dimensions of fracture toughness implies that classical failure scaling is at work. Classical fracture mechanics is a damage process that likely will not saturate and that we then are able to extrapolate to large sizes. We discuss impactors that would be used to deflect asteroids or comet nuclei for planetary defense or for engineering and exploration purposes, and what expected momentum enhancements would be for impacts into asteroids or comet nuclei comprised of consolidated materials.

OBJECTIVE To examine the association between fatty acid binding protein 4 (FABP4) and pre-eclampsia risk in women with type 1 diabetes. RESEARCH DESIGN AND METHODS Serum FABP4 was measured in 710 women from the Diabetes and Pre-eclampsia Intervention Trial (DAPIT) in early pregnancy and in the second trimester (median 14 and 26 weeks’ gestation, respectively). RESULTS FABP4 was significantly elevated in early pregnancy (geometric mean 15.8 ng/mL [interquartile range 11.6–21.4] vs. 12.7 ng/mL [interquartile range 9.6–17]; P < 0.001) and the second trimester (18.8 ng/mL [interquartile range 13.6–25.8] vs. 14.6 ng/mL [interquartile range 10.8–19.7]; P < 0.001) in women in whom pre-eclampsia later developed. Elevated second-trimester FABP4 level was independently associated with pre-eclampsia (odds ratio 2.87 [95% CI 1.24–6.68], P = 0.03). The addition of FABP4 to established risk factors significantly improved net reclassification improvement at both time points and integrated discrimination improvement in the second trimester. CONCLUSIONS Increased second-trimester FABP4 independently predicted pre-eclampsia and significantly improved reclassification and discrimination. FABP4 shows potential as a novel biomarker for pre-eclampsia prediction in women with type 1 diabetes.

The electronic and physical properties of two LTCC dielectrics (Ferro L8 and A6M) were investigated as a function of peak firing temperature. One dielectric (L8) consists of a ceramic-filled glass composite while the other (A6M) consists of a crystallizing glass. Physical properties such as shrinkage vs. firing temperature are presented in each case. In the case of the crystallizing glass, x-ray diffraction studies are presented where two crystalline phases were observed along with residual glass. The microwave electrical properties of both materials were measured at a nominal frequency of 10 GHz. The two materials show very different relative permittivity and loss tangent dependence on firing temperature due to the different physical manner in which the final, fired state is achieved — crystallization in terms of A6M and vitreous densification in terms of L8. The dependence of conductivity on firing temperature for a typical gold conductor system (CN30-080M) compatible with both dielectrics is also presented.

A new and unique experimental configuration was developed and demonstrated to measure the inhomogeneous deformation of heterogeneous materials during flyer plate impact tests. Flyer plate experiments were performed on a granite material with a small scale structure; strain rates ranged from 105 to 107 s−1. A cross section of an impacted target was monitored and photographed during, and immediately following, passage of the shock wave through the material. Up to fourteen images were taken during passage of the shock wave. This was accomplished using an ultra-high speed Imacon camera with very short exposure times; for example, in one experiment the exposure time was 5 nanoseconds with a framing rate of 5 million frames per second. Continuous wave lasers were used as the illumination source. Edge and notch filters were used to lessen the intensity of the impact flash in the image. The photographic data was analyzed using a digital image correlation (DIC) system. These experiments examined inhomogeneous defo...

OBJECTIVE To assess the relationship between second and third trimester glycemic control and adverse outcomes in pregnant women with type 1 diabetes, as uncertainty exists about optimum glycemic targets. RESEARCH DESIGN AND METHODS Pregnancy outcomes were assessed prospectively in 725 women with type 1 diabetes from the Diabetes and Pre-eclampsia Intervention Trial. HbA1c (A1C) values at 26 and 34 weeks’ gestation were categorized into five groups, the lowest, RESULTS An A1C of 6.0–6.4% (42–47 mmol/mol) at 26 weeks’ gestation was associated with a significantly increased risk of large for gestational age (LGA) (odds ratio 1.7 [95% CI 1.0–3.0]) and an A1C of 6.5–6.9% (48–52 mmol/mol) with a significantly increased risk of preterm delivery (odds ratio 2.5 [95% CI 1.3–4.8]), pre-eclampsia (4.3 [1.7–10.8]), need for a neonatal glucose infusion (2.9 [1.5–5.6]), and a composite adverse outcome (3.2 [1.3–8.0]). These risks increased progressively with increasing A1C. Results were similar at 34 weeks’ gestation. Glucose data showed less consistent trends, although the risk of a composite adverse outcome increased with preprandial glucose levels between 6.0 and 6.9 mmol/L at 34 weeks (3.3 [1.3–8.0]). CONCLUSIONS LGA increased significantly with an A1C ≥6.0 (42 mmol/mol) at 26 and 34 weeks' gestation and with other adverse outcomes with an A1C ≥6.5% (48 mmol/mol). The data suggest that there is clinical utility in regular measurement of A1C during pregnancy.

Numerical models of unidirectional panels of ultra-high-molecular weight polyethylene (UHMWPE), like Dyneema® HB80 or Spectra®, have been a difficult challenge. The problem arises from the intimate structure of the material. It is a huge collection of fibers loosely held together by a matrix. For example, for HB80 the fibers are very small in diameter (∼17 μm) but extremely strong (∼3.5 GPa). The amount of matrix is small (∼20% in volume) and very weak. The “natural” scale to use in the numerical model for this material is the fiber scale (∼17 μm). This scale would provide the right sound speed, transverse wave speed, failure strain, strength of the laminate, deflection, slippage between the fibers/layers, etc. which are all essential details if we want to have predictive capability. But even with the very powerful computers available nowadays we are still very far from being able to simulate a real-size laminated target (for example 30 cm wide and 1 or 2 cm thick) at the fiber scale. This paper proposes an “intermediate” scale that bundles or consolidates many fibers together so that the numerical problem is solvable in a few hours (or maximum one or two days for thick targets) of computation in a single board (24 processors). The scale is chosen precisely so that the essential physics of the ballistics problem is kept and the material properties used are the ones measured in the lab for the fiber and matrix. A similar approach was presented in a previous paper for fabrics (Kevlar, Dyneema, and PBO) where a yarn-level model was able to reproduce both the wave propagation patterns and the ballistic limits. This paper first describes new material test results (shear and compression at low and high confinement pressures). These were essential in properly capturing the delamination of the material. Then, for completeness, transverse wave propagation and ballistics results in Dyneema published elsewhere are briefly presented. Finally the numerical model in LS-DYNA is developed and comparison with deflection history and ballistic limits is conferred.

Romantic relationships are central in the lives of young people. This paper uses data on romantic relationships from urban youth in the USA to illustrate how using a relationships perspective in HIV/STI and pregnancy prevention programmes broadens the skills and content covered, and contextualises the learning to enhance relevance and use. Self-report survey data were collected using electronic handheld devices for a school-based randomised trial. The survey sample includes 911 young people (mean age = 12.4 years) representative of their schools. Logistic regressions explored associations between selected sexual behaviours and relationship characteristics. For all participants, having more boy/girlfriends, dating alone, ever touching and ever having had oral sex were associated with an increased likelihood of having vaginal sex. Among young people with current partners, having a partner three or more years older, length of relationship and ever having oral sex were associated with an increased likelihood ...

Among the more technically practical methods of deflecting a potentially hazardous object (PHO) is kinetic impact, whereby the momentum change imparted to the object by the cratering impact of a targeted spacecraft or other projectile affects the required minor orbital change to avert impending disaster. The ratio of the momentum change of the target to the impact momentum is commonly denoted as β, the momentum enhancement factor. Knowledge of what values of β to expect for impacts into near-Earth asteroids (NEAs) in the range of size and composition representative of objects in the known population of PHOs is thus crucial in designing and planning for mitigation strategies focused on the kinetic impact method. We present results of laboratory impact experiments, conducted with targets ranging in size from decimeter to meter size scales and measuring β in the process. Our impact experiments utilize the Southwest Research Institute’s (SwRI) 50-mm powder gun, which can fire up to 260-g mass projectiles at speeds of ~2 km/s, supplemented by smaller-scale experiments using the NASA Ames Vertical Gun Range (AVGR) as necessary to study a parameter space that includes projectile mass, speed, composition, impact angle as well as target mass composition and temperature. Targets are mounted to allow recoil (on a conventional ballistic pendulum) and all impact experiments are documented by high-speed video allowing the required analysis to quantify impact outcome and target recoil. To date we have completed 29 small-scale shots at the AVGR and 24 large-scale shots with the SwRI 50-mm powder gun. AVGR experiments include 13 shots into 10.2-cm and 15.2-cm right cylinders composed of a plaster-sand mix as a porous silicate asteroid analog, two shots into 15.2-cm pumice cubes, and 14 shots into 10.2-cm right cylinders of an iron-nickel alloy approximating the composition of iron meteorites. β values of ~1–2 and ~1.3 were obtained for the plaster-sand mix and the pumice, respectively, and ~1.7–2 for the iron-nickel shots, performed at temperatures of about 297 K and 149 K, thus spanning the ductile to-brittle fracture transition. For the metal target shots we see what appears to be a trend to higher β for higher speed shots and for the cryo shots. SwRI 50-mm powder gun shots were conducted with large pieces of pumice, concrete, and sandstone impacted with 2.54-cm and 4.45-cm aluminum projectiles at impact speeds of ~2.0 km/s. Although the pumice targets do not show a size scale effect and data from the sandstone shots are still being analyzed, the concrete material does show a significant size scale effect. Additional shots are planned for meter-scale targets composed of the same plaster-sand mix previously shot at decimeter scale at the AVGR.

An unknown in deflecting an asteroid on a collision course with Earth is the quantitative effectiveness of various deflection techniques. For example, when an impactor strikes a body at hypervelocities the momentum transferred to the impacted body is greater than the initial impactor momentum due to the crater ejecta. When the impacted body’s mass provides some of the momentum change, the effect is referred to as momentum enhancement. The small amount of data on this question implies that there is a scale effect – that is, as the projectile size increases there is an increase in the imparted momentum beyond that anticipated due to the increase in projectile size. Recently, experimental data was gathered on the increase in momentum caused by crater ejecta when 4.45-cm diameter aluminum spheres struck granite targets. The amount of momentum enhancement (characterized by the ratio β) was greater than 2 for 2 km/s impacts. Compared with other data at much smaller scale, these tests imply an impactor scale and an impactor density effect for hypervelocity strikes into rock. The implied impactor size scale effect is surprisingly large–to a 0.4 power–and extrapolation indicates that a 1-m aluminum sphere striking a consolidated rock surface at 10 km/s could have a β exceeding 40, though the scale size saturation may be just larger than the tests we performed, which would reduce this value. Such a potentially large momentum enhancement shows that kinetic impactors can be very efficient at deflecting asteroids. Also, the failure strain is shown to depend on the scale size to the −2/3 power.

Background: Diabetes prevalence in Scotland is increasing at approximately 4.6% annually, with figures currently at 247,278 (4.7%). Internet-based interventions have the potential to enhance self-management and shift the balance of power towards the patient. Electronic personal health records (ePHRs) have been identified as an ideal route to deliver these interventions, as outlined in the Department of Health Information Strategy. Methods: We developed a diabetes-focused, population-based ePHR for NHS Scotland. Data are sourced from primary, secondary and tertiary care via the national shared-electronic record, SCI-DC. Data are displayed alongside lay-descriptions and information links tailored to the patient’s needs. Results: 3,391 individuals have registered to access their clinical data. In this largely self-selecting group, 31% have type 1 diabetes and 61% are male. 2,015 have completed the enrolment process and 861 have successfully logged in. By the end of 2012, the number of distinct users per month had risen to nearly 300. Conclusions: The system is now a useful additional component for the self-management of diabetes. Although the system has been developed for, and by, stakeholders from across Scotland, it has the potential to connect to any electronic medical record. The current project is expected to reach over 5,000 patients by the end of 2013.

When an impactor strikes a body at hypervelocities the momentum transferred to the impacted body is greater than the initial impactor momentum. This effect is due to the crater ejecta, and when the impacted body's mass provides some of the momentum change, the effect is referred to as momentum enhancement. The small amount of data on this question implies that there is a scale effect – that is, as the projectile size increases there is an increase in the imparted momentum beyond that anticipated due to the increase in projectile size. Recently, experimental data was gathered on the increase in momentum caused by crater ejecta when 4.45-cm diameter aluminum spheres struck granite targets. The amount of momentum enhancement (characterized by the ratio β) was greater than 2 for 2 km/s impacts. Compared with other data at much smaller scale, these tests imply an impactor scale and an impactor density effect for hypervelocity strikes into rock. The implied impactor size scale effect is surprisingly large – to a 0.4 power – and extrapolation indicates that a 1-meter aluminum sphere striking a consolidated rock surface at 10 km/s could have a β exceeding 40, supposing the scale size effect does not saturate on the order of 10 cm. Such a large momentum enhancement shows that kinetic impactors can be very efficient at deflecting asteroids.

OBJECTIVE To assess the relationship between glycemic control, pre-eclampsia, and gestational hypertension in women with type 1 diabetes. RESEARCH DESIGN AND METHODS Pregnancy outcome (pre-eclampsia or gestational hypertension) was assessed prospectively in 749 women from the randomized controlled Diabetes and Pre-eclampsia Intervention Trial (DAPIT). HbA1c (A1C) values were available up to 6 months before pregnancy (n = 542), at the first antenatal visit (median 9 weeks) (n = 721), at 26 weeks’ gestation (n = 592), and at 34 weeks’ gestation (n = 519) and were categorized as optimal ( RESULTS Pre-eclampsia and gestational hypertension developed in 17 and 11% of pregnancies, respectively. Women who developed pre-eclampsia had significantly higher A1C values before and during pregnancy compared with women who did not develop pre-eclampsia (P < 0.05, respectively). In early pregnancy, A1C ≥8.0% was associated with a significantly increased risk of pre-eclampsia (odds ratio 3.68 [95% CI 1.17–11.6]) compared with optimal control. At 26 weeks’ gestation, A1C values ≥6.1% (good: 2.09 [1.03–4.21]; moderate: 3.20 [1.47–7.00]; and poor: 3.81 [1.30–11.1]) and at 34 weeks’ gestation A1C values ≥7.0% (moderate: 3.27 [1.31–8.20] and poor: 8.01 [2.04–31.5]) significantly increased the risk of pre-eclampsia compared with optimal control. The adjusted odds ratios for pre-eclampsia for each 1% decrement in A1C before pregnancy, at the first antenatal visit, at 26 weeks’ gestation, and at 34 weeks’ gestation were 0.88 (0.75–1.03), 0.75 (0.64–0.88), 0.57 (0.42–0.78), and 0.47 (0.31–0.70), respectively. Glycemic control was not significantly associated with gestational hypertension. CONCLUSIONS Women who developed pre-eclampsia had significantly higher A1C values before and during pregnancy. These data suggest that optimal glycemic control both early and throughout pregnancy may reduce the risk of pre-eclampsia in women with type 1 diabetes.

Momentum enhancement is the increase in momentum transferred to a target due to ejecta material being thrown backwards during crater formation. Quantitative estimates of momentum enhancement are of interest in determining the effectiveness of hypervelocity impactors in deflecting potentially hazardous cosmic objects. This paper explores the influence of impactor density and shape on momentum enhancement when striking aluminum, rock, and ice for impacts up to 10 km/s. Computations are performed and compared to the relatively sparse available data for validation. The computations show that momentum enhancement is most sensitive to the tensile fracture stress of the target material. Further, it is shown that for consolidated (low porosity) targets, momentum enhancement is maximized when the density of the impactor is similar to that of the target and the shape of the impactor is close to a sphere.