Effect of specimen geometry and test configuration on the fracture process zone for asphalt materials

In the United States and elsewhere in the world, recycled materials are commonly incorporated into asphalt mixtures, to provide environmental and economic benefits by decreasing the use of virgin materials, such as natural or quarried aggregates and asphalt binder, in newly designed asphalt mixtures. However, recycled materials such as reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) have resulted in asphalt mixtures prone to early cracking. In addition, Superpave volumetric design requirements are no longer sufficient to design asphalt mixtures because of the inconsistent properties of RAP or RAS. Consequently, agencies have been adopting performance tests to assess the cracking and rutting vulnerability of asphalt mixtures to achieve a balance mix design. The Illinois Flexibility Index Test (I-FIT) protocol was developed at the Illinois Center for Transportation (ICT) and published as American Association of State Highway and Transportation Officials provisional standards (AASHTO TP 124) to evaluate the cracking vulnerability of asphalt concrete. The test consists of a semi-circular asphalt concrete sample that has a vertical notch loaded along the symmetric axis resulting in mode-I type of fracture similar to, the typical three-point bending beam tests. The I-FIT global response refers to the load-versus-displacement curve that is characterized using the fracture energy (FE), strength, and post-peak slope. The microstructural response refers to the deformation occurring in the fracture process zone (FPZ). FPZ is the region surrounding the notch tip that develops micro cracks before a macro crack is observed. Hence, the energy dissipation due to the deformation that occurs in this region eventually controls the global response of the specimen. I-FIT outputs are influenced by specimen geometry and test conditions (e.g., thickness, and loading rate, as well field aging). For this reason, there is a need to understand the effect of test parameters on global and microstructural responses to calibrate the I-FIT results when test parameters are altered. Therefore, this work investigates the effect of the notch length, specimen thickness, loading rate, air void content, and asphalt binder on I-FIT global results and microstructural response. Multiple samples with varying notch lengths, thicknesses, and loading rates were evaluated to observe the effect of the test parameters. Then, samples with varying air void content and asphalt binder were tested to observe the mixture properties effect. The tests were recorded with high-resolution cameras to allow for digital image correlation (DIC) measurements. DIC measured the strain and displacement fields at a resolution of 8 microns/pixels. The resolution allows to evaluate the local characterization of fracture mechanisms and the interaction between the asphalt mastic and aggregate phases. It was found that an increase in the thickness or loading rate resulted in an increase of the post-peak slope without affecting the FE. On the other hand, an increase in the notch length or air voids content resulted in lower post-peak slope values. The FE was affected by the notch length and the loading rate. From, DIC results, it was seen that a decrease in the FPZ area correlated to a decrease in the FE and lower post-peak slope. The results from varying the notch length did not follow this trend because, as the notch length gets longer, the compressive strain (not included in the FPZ definition) interacts as an energy dissipation mechanism at failure. It can be concluded that existing correction factors that address the variation due to specimen thickness and air void content are appropriate. A new correction factor to account for the notch length is proposed. Finally, the specimen properties affect the microstructural response of the specimen. As the one of the test parameter (thickness, notch length, loading rate, or air voids) is modified, the size of the FPZ changed

Evaluation of Various Tack Coat Materials Using Interface Shear Device and Recommendations on a Simplified Device

The performance of pavement interface bonds affects the integrity of pavement structures. In current practice, tack coats are used to ensure sufficient bonding between asphalt concrete (AC) layers as well as AC and concrete or aggregate base layers. A tack coat is a light application of bituminous materials to an existing surface using a distributor to provide sufficient bonding between pavement layers (Asphalt Institute, 1989). In the past, several research studies were conducted at the Illinois Center for Transportation to evaluate the effectiveness of tack coats between two AC layers and AC and Portland Cement Concrete (PCC) surfaces. In this study, the shear strength of seven types of tack coat materials were evaluated, four of which were hot-applied tack coat products. The results show that hot-applied products have superior shear strength as compared to emulsion type products. A simplified shear testing configuration was also acquired and preliminary testing was completed to provide some recommendations for its future use by the Illinois Department of Transportation.IDOT-R27-SP34Ope

Open Data in action: Initiatives during the initial stage of the COVID-19 pandemic

The COVID-19 pandemic has increased the demand for access to timely, relevant, and quality data. This demand has been driven by several needs: taking informed policy actions quickly, improving communication on the current state of play, carrying out scientific analysis of a dynamic threat, understanding its social and economic impact, and enabling civil society oversight and reporting. Based on an open call for evidence, this report assesses how open government data (OGD) was used to react and respond to the COVID-19 pandemic during initial stage of the crisis (March-July 2020). It also seeks to transform lessons learned into considerations for policy makers on how to improve OGD policies to better prepare for future shocks

KAT-Independent Gene Regulation by Tip60 Promotes ESC Self-Renewal but Not Pluripotency

Although histone-modifying enzymes are generally assumed to function in a manner dependent on their enzymatic activities, this assumption remains untested for many factors. Here, we show that the Tip60 (Kat5) lysine acetyltransferase (KAT), which is essential for embryonic stem cell (ESC) self-renewal and pre-implantation development, performs these functions independently of its KAT activity. Unlike ESCs depleted of Tip60, KAT-deficient ESCs exhibited minimal alterations in gene expression, chromatin accessibility at Tip60 binding sites, and self-renewal, thus demonstrating a critical KAT-independent role of Tip60 in ESC maintenance. In contrast, KAT-deficient ESCs exhibited impaired differentiation into mesoderm and endoderm, demonstrating a KAT-dependent function in differentiation. Consistent with this phenotype, KAT-deficient mouse embryos exhibited post-implantation developmental defects. These findings establish separable KAT-dependent and KAT-independent functions of Tip60 in ESCs and during differentiation, revealing a complex repertoire of regulatory functions for this essential chromatin remodeling complex

Examining national and district-level trends in neonatal health in Peru through an equity lens:A success story driven by political will and societal advocacy

Abstract Background Peru has impressively reduced its neonatal mortality rate (NMR). We aimed, for the period 2000–2013, to: (a) describe national and district NMR variations over time; (b) assess NMR trends by wealth quintile and place of residence; (c) describe evolution of mortality causes; (d) assess completeness of registered mortality; (e) assess coverage and equity of NMR-related interventions; and (f) explore underlying driving factors. Methods We compared national NMR time trends from different sources. To describe NMR trends by wealth quintiles, place of residence and districts, we pooled data on births and deaths by calendar year for neonates born to women interviewed in multiple surveys. We disaggregated coverage of NMR-related interventions by wealth quintiles and place of residence. To identify success factors, we ran regression analyses and combined desk reviews with qualitative interviews and group discussions. Results NMR fell by 51 % from 2000 to 2013, second only to Brazil in Latin America. Reduction was higher in rural and poorest segments (52 and 58 %). District NMR change varied by source. Regarding cause-specific NMRs, prematurity decreased from 7.0 to 3.2 per 1,000 live births, intra-partum related events from 2.9 to 1.2, congenital abnormalities from 2.4 to 1.8, sepsis from 1.9 to 0.8, pneumonia from 0.9 to 0.4, and other conditions from 1.2 to 0.7. Under-registration of neonatal deaths decreased recently, more in districts with higher development index and lower rural population. Coverage of family planning, antenatal care and skilled birth attendance increased more in rural areas and in the poorest quintile. Regressions did not show consistent associations between mortality and predictors. During the study period social determinants improved substantially, and dramatic out-of-health-sector and health-sector changes occurred. Rural areas and the poorest quintile experienced greater NMR reduction. This progress was driven, within a context of economic growth and poverty reduction, by a combination of strong societal advocacy and political will, which translated into pro-poor implementation of evidence-based interventions with a rights-based approach. Conclusions Although progress in Peru for reducing NMR has been remarkable, future challenges include closing remaining gaps for urban and rural populations and improving newborn health with qualified staff and intermediate- and intensive-level health facilities

The Large Aperture GRB Observatory

The Large Aperture GRB Observatory (LAGO) is aiming at the detection of the high energy (around 100 GeV) component of Gamma Ray Bursts, using the single particle technique in arrays of Water Cherenkov Detectors (WCD) in high mountain sites (Chacaltaya, Bolivia, 5300 m a.s.l., Pico Espejo, Venezuela, 4750 m a.s.l., Sierra Negra, Mexico, 4650 m a.s.l). WCD at high altitude offer a unique possibility of detecting low gamma fluxes in the 10 GeV - 1 TeV range. The status of the Observatory and data collected from 2007 to date will be presented.Comment: 4 pages, proceeding of 31st ICRC 200

Water Cherenkov Detectors response to a Gamma Ray Burst in the Large Aperture GRB Observatory

In order to characterise the behaviour of Water Cherenkov Detectors (WCD) under a sudden increase of 1 GeV - 1 TeV background photons from a Gamma Ray Burst (GRB), simulations were conducted and compared to data acquired by the WCD of the Large Aperture GRB Observatory (LAGO). The LAGO operates arrays of WCD at high altitude to detect GRBs using the single particle technique. The LAGO sensitivity to GRBs is derived from the reported simulations of the gamma initiated particle showers in the atmosphere and the WCD response to secondaries.Comment: 5 pages, proceeding of the 31st ICRC 200

Arf4 is required for Mammalian development but dispensable for ciliary assembly

The primary cilium is a sensory organelle, defects in which cause a wide range of human diseases including retinal degeneration, polycystic kidney disease and birth defects. The sensory functions of cilia require specific receptors to be targeted to the ciliary subdomain of the plasma membrane. Arf4 has been proposed to sort cargo destined for the cilium at the Golgi complex and deemed a key regulator of ciliary protein trafficking. In this work, we show that Arf4 binds to the ciliary targeting sequence (CTS) of fibrocystin. Knockdown of Arf4 indicates that it is not absolutely required for trafficking of the fibrocystin CTS to cilia as steady-state CTS levels are unaffected. However, we did observe a delay in delivery of newly synthesized CTS from the Golgi complex to the cilium when Arf4 was reduced. Arf4 mutant mice are embryonic lethal and die at mid-gestation shortly after node formation. Nodal cilia appeared normal and functioned properly to break left-right symmetry in Arf4 mutant embryos. At this stage of development Arf4 expression is highest in the visceral endoderm but we did not detect cilia on these cells. In the visceral endoderm, the lack of Arf4 caused defects in cell structure and apical protein localization. This work suggests that while Arf4 is not required for ciliary assembly, it is important for the efficient transport of fibrocystin to cilia, and also plays critical roles in non-ciliary processes