Analysis of PDA measurements in double injection GDI sprays

Abstract A N-heptane spray from a GDI multi-hole injector operated in ambient air at fixed conditions and with double injection commands is studied with different experimental techniques to better understand the spray behaviors, focusing the analysis on the effect of different dwell times between the two pulses. Results from spray photographic analysis, fuel injected quantity, droplet velocity and sizing by Phase Doppler Anemometry are presented and compared. The peculiarities and usefulness of a complementary application of the different techniques is illustrated. The two spray pulses have the same time length, so that the first spray evolves in a nearly quiescent and clean ambient, while the second, nominally identical to the first one, evolves in its trailing edge. The direct comparison allows an immediate perception of the differences among the two sprays, at the different dwell times, where the shorter tested, 160 microseconds, was chosen as the one that shows the first appreciable effect with at least one of the used techniques; the differences are clearly evident in the PDA results, sufficiently visible from the injection rate, not appreciable in the imaging at short distance. The effect of the longer dwell times becomes more evident and is illustrate

Impact of the Primary Break-Up Strategy on the Morphology of GDI Sprays in 3D-CFD Simulations of Multi-Hole Injectors

The scientific literature focusing on the numerical simulation of fuel sprays is rich in atomization and secondary break-up models. However, it is well known that the predictive capability of even the most diused models is aected by the combination of injection parameters and operating conditions, especially backpressure. In this paper, an alternative atomization strategy is proposed for the 3D-Computational Fluid Dynamics (CFD) simulation of Gasoline Direct Injection (GDI) sprays, aiming at extending simulation predictive capabilities over a wider range of operating conditions. In particular, attention is focused on the eects of back pressure, which has a remarkable impact on both the morphology and the sizing of GDI sprays. 3D-CFD Lagrangian simulations of two dierent multi-hole injectors are presented. The first injector is a 5-hole GDI prototype unit operated at ambient conditions. The second one is the well-known Spray G, characterized by a higher back pressure (up to 0.6 MPa). Numerical results are compared against experiments in terms of liquid penetration and Phase Doppler Anemometry (PDA) data of droplet sizing/velocity and imaging. CFD results are demonstrated to be highly sensitive to spray vessel pressure, mainly because of the atomization strategy. The proposed alternative approach proves to strongly reduce such dependency. Moreover, in order to further validate the alternative primary break-up strategy adopted for the initialization of the droplets, an internal nozzle flow simulation is carried out on the Spray G injector, able to provide information on the characteristic diameter of the liquid column exiting from the nozzle

dMyc Functions Downstream of Yorkie to Promote the Supercompetitive Behavior of Hippo Pathway Mutant Cells

Genetic analyses in Drosophila epithelia have suggested that the phenomenon of “cell competition” could participate in organ homeostasis. It has been speculated that competition between different cell populations within a growing organ might play a role as either tumor promoter or tumor suppressor, depending on the cellular context. The evolutionarily conserved Hippo (Hpo) signaling pathway regulates organ size and prevents hyperplastic disease from flies to humans by restricting the activity of the transcriptional cofactor Yorkie (yki). Recent data indicate also that mutations in several Hpo pathway members provide cells with a competitive advantage by unknown mechanisms. Here we provide insight into the mechanism by which the Hpo pathway is linked to cell competition, by identifying dMyc as a target gene of the Hpo pathway, transcriptionally upregulated by the activity of Yki with different binding partners. We show that the cell-autonomous upregulation of dMyc is required for the supercompetitive behavior of Yki-expressing cells and Hpo pathway mutant cells, whereas the relative levels of dMyc between Hpo pathway mutant cells and wild-type neighboring cells are critical for determining whether cell competition promotes a tumor-suppressing or tumor-inducing behavior. All together, these data provide a paradigmatic example of cooperation between tumor suppressor genes and oncogenes in tumorigenesis and suggest a dual role for cell competition during tumor progression depending on the output of the genetic interactions occurring between confronted cells

dMyc Functions Downstream of Yorkie to Promote the Supercompetitive Behavior of Hippo Pathway Mutant Cells

Genetic analyses in Drosophila epithelia have suggested that the phenomenon of “cell competition” could participate in organ homeostasis. It has been speculated that competition between different cell populations within a growing organ might play a role as either tumor promoter or tumor suppressor, depending on the cellular context. The evolutionarily conserved Hippo (Hpo) signaling pathway regulates organ size and prevents hyperplastic disease from flies to humans by restricting the activity of the transcriptional cofactor Yorkie (yki). Recent data indicate also that mutations in several Hpo pathway members provide cells with a competitive advantage by unknown mechanisms. Here we provide insight into the mechanism by which the Hpo pathway is linked to cell competition, by identifying dMyc as a target gene of the Hpo pathway, transcriptionally upregulated by the activity of Yki with different binding partners. We show that the cell-autonomous upregulation of dMyc is required for the supercompetitive behavior of Yki-expressing cells and Hpo pathway mutant cells, whereas the relative levels of dMyc between Hpo pathway mutant cells and wild-type neighboring cells are critical for determining whether cell competition promotes a tumor-suppressing or tumor-inducing behavior. All together, these data provide a paradigmatic example of cooperation between tumor suppressor genes and oncogenes in tumorigenesis and suggest a dual role for cell competition during tumor progression depending on the output of the genetic interactions occurring between confronted cells

The impact of the Hippo pathway and cell metabolism on pathological complete response in locally advanced Her2+ breast cancer: the TRISKELE multicenter prospective study

The Hippo pathway and its two key effectors, Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ), are consistently altered in breast cancer. Pivotal regulators of cell metabolism such as the AMP-activated protein kinase (AMPK), Stearoyl-CoA-desaturase 1 (SCD1), and HMG-CoA reductase (HMGCR) are relevant modulators of TAZ/YAP activity. In this prospective study, we measured the tumor expression of TAZ, YAP, AMPK, SCD1, and HMGCR by immunohistochemistry in 65 Her2+ breast cancer patients who underwent trastuzumab-based neoadjuvant treatment. The aim of the study was to assess the impact of the immunohistochemical expression of the Hippo pathway transducers and cell metabolism regulators on pathological complete response. Low expression of cytoplasmic TAZ, both alone and in the context of a composite signature identified by machine learning including also low nuclear levels of YAP and HMGCR and high cytoplasmic levels of SCD1, was a predictor of residual disease in the univariate logistic regression. This finding was not confirmed in the multivariate model including estrogen receptor > 70% and body mass index > 20. However, our findings were concordant with overall survival data from the TCGA cohort. Our results, possibly affected by the relatively small sample size of this study population, deserve further investigation in adequately sized, ad hoc prospective studies

Power, Resistance, and Subjectivity: An Exploration of Overseas Korean Adoptees in Korea

This dissertation explores the lives and experiences of individuals who were born in Korea, adopted overseas as infants or young children, and have returned to their country of birth as adults. More specifically, I present the diverse, creative, and sometimes subtle ways in which adoptee returnees have engaged in resistance in order to reclaim their right to reside in Korea, access their personal histories, and challenge the system that produced their subjectivities as overseas Korean adoptees. Ranging from everyday practices, such as cross-cultural or linguistic code-switching, to grassroots activism and coalition building, this broad spectrum of resistance practices elucidates the ways power manifests itself in several forms in Korean society, the state, and the adoption industry. Throughout this study, I draw on the theoretical contributions of Michel Foucault, which have greatly shaped our understandings of power in its ubiquity and multi-dimensionality, and Michel de Certeau’s concepts of strategies, tactics, and resistance against power in daily life practices. I approach the interactions of power and resistance as inherently dynamic, open-ended, unpredictable, and constantly shifting rather than assume direct causation or the necessary presence of intention or consciousness. I argue that all these practices, including the act of return to a place from where these adoptee returnees were adopted away in previous decades, signify resistance against existing systems of power. In an attempt to disrupt conventional narratives of adoption, this study aims to focus the discussion on those who have been directly affected by Korea’s inadequate social welfare system and the institution of overseas adoption: adoptees, families of origin, single mother families, and other vulnerable members of Korean society. Broken down into an introduction, three main chapters, and a conclusion, this study is an ethnography that conceptualizes power and resistance through narratives. I present a historical overview of adoption practices in Korea starting from the mid- and late Chosǒn dynasty and continuing up to current overseas and domestic adoption practices. Additionally, I situate the return of Korean adoptees to Korea and their everyday practices and modes of consumption within the history of overseas Korean adoption. Next, I focus on original family search and reunion among adoptees, which includes a debate surrounding access to adoption records and personal histories. The discussion then shifts to a coalition that has formed among adult adoptee returnees, unwed and single mothers, original Korean family members who have been separated from a child or children through Korean adoption practices, a Korean pastor and his wife who run an adoptee guesthouse in Seoul, and other allies, highlighting their mobilization strategies and political activism. Finally, I consider how utilizing a social justice and human rights framework facilitates a more holistic understanding of the history of Korean adoption and the lives that have been directly affected by adoption practices

Power, Resistance, and Subjectivity: An Exploration of Overseas Korean Adoptees in Korea

This dissertation explores the lives and experiences of individuals who were born in Korea, adopted overseas as infants or young children, and have returned to their country of birth as adults. More specifically, I present the diverse, creative, and sometimes subtle ways in which adoptee returnees have engaged in resistance in order to reclaim their right to reside in Korea, access their personal histories, and challenge the system that produced their subjectivities as overseas Korean adoptees. Ranging from everyday practices, such as cross-cultural or linguistic code-switching, to grassroots activism and coalition building, this broad spectrum of resistance practices elucidates the ways power manifests itself in several forms in Korean society, the state, and the adoption industry. Throughout this study, I draw on the theoretical contributions of Michel Foucault, which have greatly shaped our understandings of power in its ubiquity and multi-dimensionality, and Michel de Certeau’s concepts of strategies, tactics, and resistance against power in daily life practices. I approach the interactions of power and resistance as inherently dynamic, open-ended, unpredictable, and constantly shifting rather than assume direct causation or the necessary presence of intention or consciousness. I argue that all these practices, including the act of return to a place from where these adoptee returnees were adopted away in previous decades, signify resistance against existing systems of power. In an attempt to disrupt conventional narratives of adoption, this study aims to focus the discussion on those who have been directly affected by Korea’s inadequate social welfare system and the institution of overseas adoption: adoptees, families of origin, single mother families, and other vulnerable members of Korean society. Broken down into an introduction, three main chapters, and a conclusion, this study is an ethnography that conceptualizes power and resistance through narratives. I present a historical overview of adoption practices in Korea starting from the mid- and late Chosǒn dynasty and continuing up to current overseas and domestic adoption practices. Additionally, I situate the return of Korean adoptees to Korea and their everyday practices and modes of consumption within the history of overseas Korean adoption. Next, I focus on original family search and reunion among adoptees, which includes a debate surrounding access to adoption records and personal histories. The discussion then shifts to a coalition that has formed among adult adoptee returnees, unwed and single mothers, original Korean family members who have been separated from a child or children through Korean adoption practices, a Korean pastor and his wife who run an adoptee guesthouse in Seoul, and other allies, highlighting their mobilization strategies and political activism. Finally, I consider how utilizing a social justice and human rights framework facilitates a more holistic understanding of the history of Korean adoption and the lives that have been directly affected by adoption practices

A simplified evaluation of the influence of the bond pattern on the brickwork limit strength

The influence of the bond pattern on the in-plane limit strength of masonry is analyzed through a simplified procedure based on the application of the safe theorem of limit analysis to the unit cell that generates the whole masonry by periodic repetition. The limit strength domains of running bond, English bond and herringbone bond masonry are obtained with different orientations of the mortar bed joints with respect to the principal directions of the average stress. The effects of different brick geometries are analyzed and comparisons between strength properties of different masonry patterns are made

Influence of crack wake mechanisms on the dynamic fracture of multiply delaminated plates

The paper deals with the dynamic interaction of multiple delaminations in composite plates subject to out of plane loading. In order to develop a basic understanding of the problem, the work refers to the model system of a multiply delaminated plate deforming in cylindrical bending. Interaction effects on fracture parameters, dynamic crack growth, energy absorption and damage and impact tolerance are investigated. Large scale crack bridging mechanisms, such as those produced by a through-thickness reinforcement, strongly control and regularize the dynamic response of systems of stationary delaminations. In the free vibration phase that follows the removal of the load, the crack bridging action developed by a typical through-thickness reinforcement prevents out of phase vibrations and hammering of the delaminated layers and limits amplification of the fracture parameter