Academic literature on the topic 'And Al-Bayyati's loss functions'
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Journal articles on the topic "And Al-Bayyati's loss functions"
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Arun, Kumar Rao, and Pandey Himanshu. "ESTIMATION OF SCALE PARAMETER OF WEIBULL-LOMAX DISTRIBUTION VIA BAYESIAN APPROACH." International Journal of Mathematics And Computer Research 09, no. 05 (2021): 2293–302. https://doi.org/10.47191/ijmcr/v9i5.03.
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In this paper, the Weibull-Lomax distribution is considered for Bayesian analysis. The expressions for Bayes estimators of the parameter have been derived under squared error, precautionary,entropy, K-loss, and Al-Bayyati’s loss functions by using quasi and gamma priors.
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Uma, Alexandra, Tommaso Fornaciari, Dirk Hovy, Silviu Paun, Barbara Plank, and Massimo Poesio. "A Case for Soft Loss Functions." Proceedings of the AAAI Conference on Human Computation and Crowdsourcing 8 (October 1, 2020): 173–77. http://dx.doi.org/10.1609/hcomp.v8i1.7478.
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Recently, Peterson et al. provided evidence of the benefits of using probabilistic soft labels generated from crowd annotations for training a computer vision model, showing that using such labels maximizes performance of the models over unseen data. In this paper, we generalize these results by showing that training with soft labels is an effective method for using crowd annotations in several other ai tasks besides the one studied by Peterson et al., and also when their performance is compared with that of state-of-the-art methods for learning from crowdsourced data.
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Kircher, Charles A., Aladdin A. Nassar, Onder Kustu, and William T. Holmes. "Development of Building Damage Functions for Earthquake Loss Estimation." Earthquake Spectra 13, no. 4 (1997): 663–82. http://dx.doi.org/10.1193/1.1585974.
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This paper describes building damage functions that were developed for the FEMA/NIBS earthquake loss estimation methodology (Whitman et al., 1997). These functions estimate the probability of discrete states of structural and nonstructural building damage that are used as inputs to the estimation of building losses, including economic loss, casualties and loss of function (Kircher et al., 1997). These functions are of a new form and represent a significant step forward in the prediction of earthquake impacts. Unlike previous building damage models that are based on Modified Mercalli Intensity, the new functions use quantitative measures of ground shaking (and ground failure) and analyze model building types in a similar manner to the engineering analysis of a single structure.
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Prahl, B. F., D. Rybski, O. Burghoff, and J. P. Kropp. "Comparison of storm damage functions and their performance." Natural Hazards and Earth System Sciences 15, no. 4 (2015): 769–88. http://dx.doi.org/10.5194/nhess-15-769-2015.
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Abstract. Winter storms are the most costly natural hazard for European residential property. We compare four distinct storm damage functions with respect to their forecast accuracy and variability, with particular regard to the most severe winter storms. The analysis focuses on daily loss estimates under differing spatial aggregation, ranging from district to country level. We discuss the broad and heavily skewed distribution of insured losses posing difficulties for both the calibration and the evaluation of damage functions. From theoretical considerations, we provide a synthesis between the frequently discussed cubic wind–damage relationship and recent studies that report much steeper damage functions for European winter storms. The performance of the storm loss models is evaluated for two sources of wind gust data, direct observations by the German Weather Service and ERA-Interim reanalysis data. While the choice of gust data has little impact on the evaluation of German storm loss, spatially resolved coefficients of variation reveal dependence between model and data choice. The comparison shows that the probabilistic models by Heneka et al. (2006) and Prahl et al. (2012) both provide accurate loss predictions for moderate to extreme losses, with generally small coefficients of variation. We favour the latter model in terms of model applicability. Application of the versatile deterministic model by Klawa and Ulbrich (2003) should be restricted to extreme loss, for which it shows the least bias and errors comparable to the probabilistic model by Prahl et al. (2012).
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KAMIL, MUH AHSAN, and YAHYA RIVA'I. "EMPOWERING SHARIA SECURITIES: IMPLEMENTING AN ISSUERS' MENTORING PROGRAM FOR LOSS MITIGATION IN CROWDFUNDING." Al-Masraf: Jurnal Lembaga Keuangan dan Perbankan 8, no. 2 (2023): 207. http://dx.doi.org/10.15548/al-masraf.v8i2.834.
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This study aims to implement a mentoring program for issuers (MSMEs) in sharia securities crowdfunding in Indonesia to mitigate the losses. A qualitative approach was used, using in-depth literature studies with relevant stakeholders and analyzing secondary data. The data was then analyzed by reducing data, displaying data and verifying. The research findings highlight that in the Sharia securities crowdfunding mechanism, the organizer only functions as a platform that brings together investors and issuers. Therefore, in this research, the author recommends a mentoring program for MSME issuers that organizers of Sharia crowdfunding securities can implement. This recommendation is based on the general weaknesses of MSMEs, which can cause the risk of losses and defaults. With this mentoring program, it is hoped that publishers' businesses can avoid the risk of loss and continue to grow to benefit all parties.
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Alvarez, Jose R., and Peter Rez. "Density of states calculations for Ni-Al Alloys." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 524–25. http://dx.doi.org/10.1017/s0424820100165082.
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Impurities at grain boundaries can have dramatic effects on the ductility or embrittlement of metals and metallic alloys. The mechanism for these effects is controversial, but it is believed that charge redistribution induced by the impurity atoms is responsible. Electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM) can be used to measure changes in unoccupied densities of states (DOS) when a small nanometer sized probe is moved across a grain boundary. To interpret the energy loss fine structure band theory is needed to relate the observations, which represent an angular momentum resolved density of states at a particular atomic site, to the local electronic structure in the material.We compare the Linearized Augmented Plane Wave (LAPW) and layered Korringa-Kohn-Rostoker (LKKR) methods for calculating densities of states relevant for energy loss in Ni-Al alloys. Both methods can give the angular momentum resolved densities of states at a particular site and both use the Local Density Approximation (LDA). The LAPW method allows ab initio electronic structure calculations of materials by introducing atomic spheres where the basis wave functions are approximated by solutions of a radial potential; for the interstitial region between the atoms the basis wave functions are approximated by plane waves.
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Rao, Arun Kumar, and Himanshu Pandey. "BAYESIAN ESTIMATION OF SHAPE PARAMETER OF POWER LOMAX DISTRIBUTION UNDER DIFFERENT LOSS FUNCTION." Journal of Mathematical Sciences & Computational Mathematics 2, no. 2 (2021): 227–35. http://dx.doi.org/10.15864/jmscm.2204.
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In this paper, the power Lomax distribution is considered for Bayesian analysis. The expressions for Bayes estimators of the parameter have been derived under squared error, precautionary, entropy, K-loss, and Al-Bayyati’s loss functions by using quasi and gamma priors.
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Rao, Arun Kumar, and Himanshu Pandey. "Bayes Estimation of Shape Parameter of Length Biased Weibull Distribution." JTAM (Jurnal Teori dan Aplikasi Matematika) 5, no. 1 (2021): 28. http://dx.doi.org/10.31764/jtam.v5i1.3268.
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In this paper, length biased Weibull distribution is considered for Bayesian analysis. The expressions for Bayes estimators of the parameter have been derived under squared error, precautionary, entropy, K-loss, and Al-Bayyati’s loss functions by using quasi and gamma priors.
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Pandey, Himanshu. "Bayesian Estimation of the Shape Parameter of Exponentiated lomax Distribution." Research International Journal of Physics and Mathematical Sciences 01, no. 01 (2021): 001–4. http://dx.doi.org/10.37179/rijpms.000001.
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In this paper, the exponentiated Lomax distribution is considered for Bayesian analysis. The Bayes estimators of the shape parameter have been obtained under squared error, precautionary, entropy, K-loss, and Al-Bayyati’s loss functions by using quasi and gamma priors.
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Cebeci, Ismail. "Naẓarīyat al-Mukhāṭarah fī al-Iqtiṣād al-Islāmī". American Journal of Islam and Society 29, № 3 (2012): 154–57. http://dx.doi.org/10.35632/ajis.v29i3.1196.
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“Risk” is one of the key concepts in understanding modern Islamic economics.Its importance does not only stem from its place in the classicalfiqh, but also from its close relation to discussions in modern Islamic financeabout permissible ḥalāl (gain) and ribā (usury). Risk has been seenas one of the key differences between ribā and non-ribā transactions andconventional finance and Islamic finance mechanisms. While modern economicsaims to eliminate the risk entirely, principles of Islamic economicsaim to establish a balance among parties through risk sharing. Becausegaining money from money is ḥarām, the risk issue is more critical in debt-based finance. In this context, it’s a controversial issue among Islamic finance scholars that Islamic banks take several precautions to completelyeliminate the risk from their transactions – although Islamic finance isknown as a profit-loss-sharing system.Adnan ‘Uwaidah’s book Risk Theory in Islamic Economics, which isbased on his doctoral dissertation, aims at theorizing risk in a legal andeconomic framework and explaining its functions. The book, which claimsto be the first academic book about risk from the Islamic legal point ofview, consists of an introduction and six main chapters. The author has a PhD from the Department of Islamic Economics and Islamic Banking atYarmouk University in Jordan, which is one of the leading institutions in this field. He shows his mastery of the topic through his academic approachto the issue, use of legal terminology, and a vast bibliography that includesclassical and modern resources ...
Books on the topic "And Al-Bayyati's loss functions"
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Rodríguez Juárez, Carolina. Accesibilidad a la función Sujeto en lengua inglesa: restricciones funcionales, intrínsecas y jerárquicas. Servicio de Publicaciones y Difusión Científica de la Universidad de Las Palmas de Gran Canaria, 2021. http://dx.doi.org/10.20420/1650.2021.479.
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La accesibilidad de un término para participar en una operación gramatical como la asignación de Sujeto está condicionada por restricciones jerárquicas, funcionales e intrínsecas que favorecerán la asignación de la función de Sujeto al primer argumento, resultando en una oración activa, o a un término distinto al primer argumento, obteniéndose una construcción pasiva. Estas restricciones se representan en forma de jerarquías de carácter tipológico cuya relevancia ha sido enfatizada tanto en la teoría de la Gramática Funcional (Dik, 1978, 1989) como en la Gramática Discursivo-Funcional (Hengeveld y Mackenzie, 2008, 2011) y cuya validez no solo está demostrada en estudios realizados entre lenguas, sino también en el caso de lenguas individuales al permitir determinar qué categorías son estadísticamente más frecuentes y consecuentemente menos marcadas en una lengua en particular. A través de un estudio cuantitativo y multidimensional basado en el análisis de un corpus escrito formado por oraciones activas transitivas y pasivas en lengua inglesa, estudiamos la incidencia directa de siete jerarquías de prioridad en la selección de Sujeto: Jerarquía de Funciones Semánticas, de Definición, de Persona, de Animacidad, de Número, de Entidades/ Abstracción, de Predicación y la Jerarquía de Términos. Los resultados demuestran que se observan preferencias de unas jerarquías sobre otras a la hora de determinar la accesibilidad de los términos a la función sintáctica de Sujeto. Basándonos en los niveles de frecuencia y de dominancia registrados entre las jerarquías, presentamos una nueva jerarquía que predice qué prioridades son más dominantes en esta operación gramatical. Estas prioridades se agrupan y ordenan jerárquicamente en tres grandes bloques atendiendo al tipo de restricciones que expresan: restricciones relacionadas con la complejidad estructural y movilidad sintáctica del término; restricciones intrínsecas del término asociadas con operadores gramaticales; y restricciones atribuibles al referente del término. Accessibility to the Subject function in the English language: functional, intrinsic and hierarchical restrictions The accessibilty of terms in grammatical operations such as Subject assignment is constrained by hierarchical, functional and intrinsic restrictions that will either trigger the assignment of the Subject function to a first argument resulting in an active sentence, or to a non-first argument, which will produce a passive sentence. These restrictions are represented in the form of typological hierarchies whose relevance has been stressed both in the theory of Functional Grammar (Dik, 1978, 1989) and in Functional Discourse Grammmar (Hengeveld y Mackenzie, 2008, 2011), and whose validity has been tested not only in studies across languages but also in the case of individual languages since they are able to determine what categories are statistically more frequent and, as a result, less marked in a particular language. Through a quantitative and multidimensional study based on a written corpus of active and passive sentences in English, we explore the direct impact of seven priority hierarchies on Subject selection: the Semantic Function Hierarchy, the Definiteness Hierarchy, the Person Hierarchy, the Animacy Hierarchy, the Number Hierarchy, the Entities/Abstraction Hierarchy, the Predication Hierarchy and the Term Hierarchy. The results reveal that preferences of some hierarchies over others can be observed when determining the accessibility of terms to the Subject function. Taking as a basis the frequency and dominance levels registered for the different hierarchies, we present a new hierarchy that predicts what priorities are more dominant in this grammatical operation. These priorites are grouped and ordered in a hierarchical fashion into three big blocks according to the type of constraints they express: restrictions related to the structural complexity and syntactic mobility of the term; intrinsic restrictions of the term associated with grammatical operators; and restrictions related to the referent of the term.
Book chapters on the topic "And Al-Bayyati's loss functions"
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Cavender-Bares, Jeannine, John A. Gamon, and Philip A. Townsend. "The Use of Remote Sensing to Enhance Biodiversity Monitoring and Detection: A Critical Challenge for the Twenty-First Century." In Remote Sensing of Plant Biodiversity. Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-33157-3_1.
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AbstractImproved detection and monitoring of biodiversity is critical at a time when the Earth’s biodiversity loss due to human activities is accelerating at an unprecedented rate. We face the largest loss of biodiversity in human history, a loss which has been called the “sixth mass extinction” (Leakey 1996; Kolbert 2014), given that its magnitude is in proportion to past extinction episodes in Earth history detectable from the fossil record. International efforts to conserve biodiversity (United Nations 2011) and to develop an assessment process to document changes in the status and trends of biodiversity globally through the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (Díaz et al. 2015) have raised awareness about the critical need for continuous monitoring of biodiversity at multiple spatial scales across the globe. Biodiversity itself—the variation in life found among ecosystems and organisms at any level of biological organization—cannot practically be observed everywhere. However, if habitats, functional traits, trait diversity, and the spatial turnover of plant functions can be remotely sensed, the potential exists to globally inventory the diversity of habitats and traits associated with terrestrial biodiversity. To face this challenge, there have been recent calls for a global biodiversity monitoring system (Jetz et al. 2016; Proença et al. 2017; The National Academy of Sciences 2017). A central theme of this volume is that remote sensing (RS) will play a key role in such a system.
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Allemeersch, Simon. "The Inside and Outside of High-Rise Social Housing: The Broken Institution." In The Urban Book Series. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-19748-2_8.
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AbstractThis article is based on an ethnographic report of a long-term artistic workplace in the inside world of a social high-rise ensemble. The communal ‘atelier’ functioned as a repair workshop (Allemeersch et al. 2014) concerned with re-negotiating the relation and knowledge between the inside and outside world. Through a synchronic ethnographic report on the inside world of the housing ensemble, this article aims to characterize the lived citizenship (Warming and Fahnøe 2017) of residents, formal and informal, based upon the opposition between formal and informal order (Goffman 1966; Scott 1998), the notion of ‘underlife’ (Goffman 1963/1996) and hidden and public transcripts (Scott 1990). As the deserted stronghold of a previously ‘pillarized’ welfare state, this article pictures an inside world that is unbalanced between formal and informal order, and lacking the latter (Scott 1998). This results in a social closure between the inside and outside world, and the loss of self of residents. Essentially, residents are caught in the double bind between isolation and social closure (Wacquant 2008) on the one hand, and the loss of façade (Goffman 1959/2019) on the other. Without a qualitative understanding of the inside world of high-rise social housing the outside world institutions act without any knowledge of ‘the community that many residents were able to create in such adverse conditions’ (Goetz 2011, p. 270), and the difficult relation these residents have developed towards their own environment and housing, state intervention and the public services (Wacquant 2008).
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Kamsu Foguem, Bernard, Pierre Tiako, and Cheick Abdoul Kadir A. Kounta. "Optimal Transport-based Loss Functions for Machine Learning." In Chronicle of Computing. Oklahoma International Publishing, 2024. http://dx.doi.org/10.55432/978-1-6692-0005-5_10.
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This short paper briefly reports the essential facets of the article (Kamsu-Foguem & al., 2022) presented and discussed as a Journal First paper. The article overviews generative neural networks whose loss functions are based on optimal transport with the Wasserstein distance. This tool of mathematical origin allows interesting automatic learning to be obtained in a reasoning time under Lipschitz constraints. As the proposed studies are based on Wasserstein Generative Adversarial Networks (WGAN), we conclude this report with a short discussion on how WGAN currently supports critical, intelligent applications in our society and nearly all industry sectors.
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Ahmad Reshi, Javaid, Bilal Ahmad Para, and Shahzad Ahmad Bhat. "Parameter Estimation of Weighted Maxwell-Boltzmann Distribution Using Simulated and Real Life Data Sets." In Adaptive Filtering - Recent Advances and Practical Implementation. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100227.
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This paper deals with estimation of parameters of Weighted Maxwell-Boltzmann Distribution by using Classical and Bayesian Paradigm. Under Classical Approach, we have estimated the rate parameter using Maximum likelihood Estimator. In Bayesian Paradigm, we have primarily studied the Bayes’ estimator of the parameter of the Weighted Maxwell-Boltzmann Distribution under the extended Jeffrey’s prior, Gamma and exponential prior distributions assuming different loss functions. The extended Jeffrey’s prior gives the opportunity of covering wide spectrum of priors to get Bayes’ estimates of the parameter – particular cases of which are Jeffrey’s prior and Hartigan’s prior. A comparative study has been done between the MLE and the estimates of different loss functions (SELF and Al-Bayyati’s, Stein and Precautionary new loss function). From the results, we observe that in most cases, Bayesian Estimator under New Loss function (Al-Bayyati’s Loss function) has the smallest Mean Squared Error values for both prior’s i.e., Jeffrey’s and an extension of Jeffrey’s prior information. Moreover, when the sample size increases, the MSE decreases quite significantly. These estimators are then compared in terms of mean square error (MSE) which is computed by using the programming language R. Also, two types of real life data sets are considered for making the model comparison between special cases of Weighted Maxwell-Boltzmann Distribution in terms of fitting.
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Cryer, Philip E. "Physiological Responses to Hypoglycemia." In Hypoglycemia. Oxford University PressNew York, NY, 1997. http://dx.doi.org/10.1093/oso/9780195113259.003.0004.
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Abstract Falling plasma glucose concentrations trigger a characteristic series of responses: decreased insulin secretion, increased glucose counter regulatory hormone secretion and autonomic neural activation, a variety of symptoms and signs, and impairment of cognitive functions (Cryer, 1993). The sequential glycemic thresholds for these responses have been quantitated (Schwartz et al., 1987; Mitrakou et al., 1991; Fanelli et al., 1994). Lower plasma glucose concentrations can cause a seizure, loss of consciousness, or both.
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Bachevalier, Jocelyne, and Ludise Malkova. "Neuropsychological Indices of Early Medial Temporal Lobe Dysfunction in Primates." In Cerebral Reorganization of Function After Brain Damage. Oxford University PressNew York, NY, 2000. http://dx.doi.org/10.1093/oso/9780195120264.003.0002.
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Abstract Neural plasticity and reorganization of brain functions have been clearly demonstrated in young animals and children after early insult to the brain. The pioneering work of Margaret Kennard (1936) in this domain has led to the proposal that early damage to the brain results in a greater sparing of brain functions than later injury. Although the Kennard principle has been substantiated by numerous studies in animals as well as humans (Bates, 1992; Goldman-Rakic et al., 1983; Kolb & Whishaw, 1989; and other chapters in this volume), other reports indicate that early brain lesions may produce different results, depending on which neural structures are removed, which brain functions are investigated, and at what age the damage occurs (Schneider, 1979). After investigating a number of human patients of early brain lesions, Teuber and colleagues (1962) suggested the existence of more than just quantitative differences in the degree of sparing or loss of function between early and late injury. For example, in some cases the early injury led to apparently anomalous functions that had never been observed in adult-injured patients (Rudel, et al., 1966; Rudel & Teuber 1971; Woods & Teuber, 1978).
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Lee, Wen-Hwa, David Goodrich, and Eva Lee. "Cancer suppression by the retinoblastoma gene." In The Legacy of Cell Fusion. Oxford University PressOxford, 1994. http://dx.doi.org/10.1093/oso/9780198547723.003.0016.
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Abstract A concentrated effort toward the molecular cloning of cancer suppressor genes had an important recent success: a candidate retinoblastoma (RB)gene was cloned, identified, and extensively characterized by us and others (Friend et al. 1986; Fung et al. 1987; Lee et al. 1987a). Our demonstration of the tumour suppression activity of this single gene when transferred into tumour cells containing inactivated endogenous RBgenes constituted a critical milestone for the theory of cancer suppression (Huang et al. 1988). Since several other cancers are known to be familial, are associated with chromosomal deletions, or exhibit loss of heterozygosity, an extension of this concept to other genes and to other cancers is widely anticipated (Malkin et al. 1990).The existence of inactivating mutations of RB in some natural human tumours supports the idea that RBnormally functions to prevent tumour formation in susceptible precursor cells (Dryja et al. 1986; Friend et al. 1987; Harbour et al. 1988; Lee et al. 1988; T’ Ang et al. 1988; Toguchida et al. 1988; Yokota et al. 1988; Horowitz et al. 1989, 1990; Reissmann et al. 1989; Shew et al. 1989, 1990b; Bookstein et al. 1990b; Cheng et al. 1990).
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Nieschlag, Eberhard. "Definitions and classification of disorders." In Oxford Textbook of Endocrinology and Diabetes. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199235292.003.9004.
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The testes have a dual function: production of male gametes and synthesis of testosterone. Their loss or loss of function does not lead to a life-threatening condition, but is incompatible with procreation. The ultimate role of testosterone is to ensure the transfer of sperm to the female and thus facilitate reproduction. However, testosterone acts on practically all organs and tissues in the body, having many functions which are seemingly not aimed exclusively at reproduction. In general, testosterone is responsible for ‘ maleness’ and thus for all features of the male phenotype, metabolism, and character. Testosterone is responsible for the differences between the sexes and thus has implications ranging from biology to sociocultural aspects. In a negative sense, its actions can be studied in individuals lacking testosterone and—in a positive sense—in these individuals receiving testosterone replacement therapy. Female-to-male transsexuals under testosterone treatment may also contribute to understanding of testosterone effects. As the dominating factor of maleness, testosterone exerts its activity throughout all phases of life. Therefore, endocrinology forms the backbone of andrology as the medical discipline dealing with male reproductive functions under physiological and pathological conditions. Andrology encompasses gonadal dysfunction in puberty, adulthood, and senescence, and deals with problems such as erectile dysfunction and male contraception. The object of andrology may be summarized as ‘ male reproductive health‘. Since a textbook of endocrinology can deal with only some, albeit important, aspects of male reproductive health, the reader is referred to specialized monographs for a more complete description of the field of andrology, e.g. Nieschlag et al . (1). In this volume, various aspects of male endocrinology are dealt with throughout, such that an integrated view of male endocrinology can only be obtained by referring to other chapters of this book. This chapter provides a classification of disorders of testicular function based on localization of cause.
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Maher, Eamonn R. "VHL and von Hippel–Lindau Disease." In Inborn Errors Of Development. Oxford University PressNew York, NY, 2008. http://dx.doi.org/10.1093/oso/9780195306910.003.0131.
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Abstract Von Hippel–Lindau (VHL) disease is a dominantly inherited familial cancer syndrome caused by germline mutations in the 3p25 VHL tumor-suppressor gene (Latif et al., 1993; Kaelin and Maher, 1998; Maher 2004; Haase, 2005; Kaelin, 2005 ). VHL is widely expressed in fetal and adult tissues, and the pattern of VHL mRNA expression in the fetal kidney is consistent with a role in normal renal tubular development and differentiation (Richards et al., 1996). Mouse models of VHL disease have demonstrated that VHL expression is critical for normal extraembryonic vascular development such that homozygous Vhlh−/− mice died in utero at 10.5–12.5 days of gestation and conditional mouse knockout models have demonstrated renal cysts but not tumors whereas in other tissues, inactivation of pVHL resulted in abnormal differentiation associated with decreased cell proliferation, suggesting tissue-specific effects of Vhlh (Haase et al., 2005). Reintroduction of pVHL into VHL null renal cell carcinoma (RCC) cells suppresses tumor formation consistent with a classical tumor suppressor gene, but complex genotype–phenotype correlations in VHL disease suggest that pVHL has multiple, and tissue-specific functions. The best-studied function of pVHL is its role as a component of an E2 ubiquitin ligase complex that regulates expression of the HIF (hypoxia inducible factor) transcription factors such that loss of pVHL is associated with HIF-induced activation of hypoxia response genes. In addition, pVHL has been implicated in normal developmental apoptosis of sympathetic neuronal precursor cells (Lee et al., 2005).
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Newbold, Paul, David I. Harvey, and Stephen J. Leybourne. "Ranking Competing Multi-Step Forecasts." In Cointigration, Causality, and forecating. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198296836.003.0004.
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Abstract Early research on methodology for the evaluation of forecasts was analyzed by Granger and New bold (1978), who proposed alternative approaches. These authors argued that a set of forecasts is most reasonably assessed through comparison with competing forecasts. This comparison could be achieved through mean squared errors of forecasts at specific horizons, though other economic loss functions such as mean absolute error or mean absolute percentage error could equally well be applied. Diebold and Mariano (1995) and Harvey et al. (1997) discuss tests of the null hypothesis of equality of performance of two competing forecasts. A second possibility, advocated by Granger and New bold, is based on the idea of combining forecasts, introduced by Bates and Granger (1969). If the optimal weight that should be attached to a particular forecast in a composite predictor which is a weighted average of the forecast and its competitor is one, that forecast is said to be conditionally efficient with respect to the competitor. Chong and Hendry (1986) then say that the forecast encompasses its competitor. Harvey et al. (1998) discuss formal hypothesis tests for forecast encompassing.
Conference papers on the topic "And Al-Bayyati's loss functions"
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Agarwala, V. S. "Corrosion Inhibition by Phenanthrolines." In CORROSION 1988. NACE International, 1988. https://doi.org/10.5006/c1988-88339.
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Abstract Phenanthrolines are primarily electron donors or cathodic inhibitors as they bond with surface metal atoms (ions) to form complexes. 1, 10-Phenanthroline and two of its derivatives were studied as corrosion inhibitors of Al 7075-T6 alloy and 1020 carbon steel. The effects of these inhibitors were studied as a function of pH, inhibitor concentration and pre-exposure conditions. Electrochemical and mass loss data showed them to be effective inhibitors for alluminum alloys. However, they were found inefficient for steel.
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Romedenne, Marie, Sebastien Dryepondt, Rishi Pillai, Michael Lance, and Bruce Pint. "High Temperature Oxidation Behavior of Fe- and Ni-Based Alloy Foils in Water Vapor at 850°C." In CORROSION 2021. AMPP, 2021. https://doi.org/10.5006/c2021-16594.
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ABSTRACT Operating temperatures above 700°C are desired to improve the efficiency of power generation systems such as microturbines. Therefore, the use of creep-resistant Ni-based or Fe-based alloys, which can form protective Cr2O3 and Al2O3 scales, is required. In this paper, Fe- and Ni-based alloy foils were oxidized in air + 10 % H2O for up to 3,000 h at 850°C to identify the most promising alloys. The thickness and chemical composition of the spinel oxide formed on top of the Cr2O3 scale varied between S3100, N08120 and N06230 alloy foils. In addition, the rate of Cr and Mn loss (spinel and Cr2O3 oxidation and volatilization) or Al loss (oxidation) and the dissolution of strengthening precipitates, were found to be a function of the nature of the formed oxide (Fe or Ni-rich spinel, Cr2O3, Al2O3). Alloys N06230 and alumina-forming austenitic (AFA) steels were found to be well-suited for the applications as microturbine recuperator foil materials up to 850°C.
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Natesan, K., and Z. Zeng. "Metal Dusting Performance of Structural Alloys." In CORROSION 2005. NACE International, 2005. https://doi.org/10.5006/c2005-05409.
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Abstract Several Ni-base alloys were tested in a high-pressure high-carbon-activity gaseous environment that simulated the effluent from a hydrogen reformer. Weight loss was measured as a function of exposure time. After exposure for ≈9,700 h at 14.3 atm (210 psia) and 593°C (1100°F), specimens were analyzed by scanning electron microscopy and Raman spectroscopy. Results showed that the metal-dusting-degradation resistance of alloys that contained a high concentration of Al and/or Cr was better than the resistance of alloys with lower concentrations of these metals. The performance of alloys with high Fe content was poor in a metal dusting environment even though these alloys contained a high concentration of Cr.; Oxide scale plays a key role in protecting the alloys from metal dusting corrosion. Raman spectra showed that the alloys can develop Cr2O3, disordered Cr oxide, and (Fe,Cr) spinel when exposed to a metal dusting environment. Cr2O3 and disordered Cr oxide were superior in resisting metal dusting corrosion, whereas the spinel phase was less resistant. The amount of spinel phase in oxide scale increases with an increase in the Fe content of the alloys, and thereby leads to the poor performance of alloys with high Fe content. The amount of spinel phase also increases with exposure time when Fe from the substrate diffuses outward into oxide scale. Results showed good correlation between weight change and the growth of a single pit, which indicates that the weight loss is due to the increase in pit size rather than to an increase in the number of pits.
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Schmitz, Andreas, Marcel Aulich, and Eberhard Nicke. "Novel Approach for Loss and Flow-Turning Prediction Using Optimized Surrogate Models in Two-Dimensional Compressor Design." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-45086.
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Two-dimensional (2D) streamline curvature methods are still an important tool in modern compressor design. In the past most of the streamline curvature methods made use of empirical correlations to approximate the blade row losses and deviation functions on which the accuracy of streamline curvature methods mainly depend. These empirical correlations are just accurate for a small set of geometric airfoil design parameters for which they where obtained and the prediction of airfoil performance at high Mach numbers or at off-design condition is inaccurate. Nowadays, a new approach is needed to consider highly customized, modern airfoil geometries with an increased number of design parameters. A new method with the possibility to predict the performance of these highly customized airfoils also at off-design condition and high Mach numbers is presented in this paper. This method uses a large airfoil database together with optimized surrogate models to accurately predict airfoil performance. The database consists of approximately 106 randomly created airfoils with randomly created inflow conditions and the airfoil performance which results from the 2D Euler-boundary layer code MISES [16]. The airfoil geometry in this database is described by ten geometrical parameters, e.g. stagger angle, chord length etc.. The flow condition is described by four flow parameters such as the relative inflow Mach number, MVDR, relative inflow angle and Reynolds number. Airfoil performance is represented by total pressure loss and flow-turning. This database was used to train neural networks that provides the relationship between the geometrical/flow parameters and the airfoil performance. The topology of the neural networks was optimized to achieve a model which represents this highly nonlinear functionality at best. This model was integrated in the DLR’s in-house streamline curvature tool ACDC which is based on the equations of MO¨NIG et al. [12], GALLIMORE [8]. The code allows viscous throughflow calculations taking into account radial mixing by turbulent diffusion, endwall boundary layers and a model for tip clearance based on the work of DENTON [7], KRO¨GER et al. [9].
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Echeverria-Villagomez, Salvador. "Metrology Investment Projects for process Effectiveness." In NCSL International Workshop & Symposium. NCSL International, 2015. http://dx.doi.org/10.51843/wsproceedings.2015.37.
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In every production process, as in every control system, there are actuator elements, measurement elements and control elements. Measurement and control are often mixed. The effectiveness of the process or the system depends very much on the proper integration and constructive balance among these functions. For intuitive reasons, most times it is easier to grasp the relevance of the actuator part in a process and more difficult to understand the relevance of the measurement part, or even the control part. That is a reason why metrology is sometimes underestimated. With the scientific conviction of the relevance of metrology for system control, CENAM has developed more than 250 projects with industry in Mexico through the MESURA Program [1,2]. Very relevant results were obtained in many of these projects and the methodology is now applied by a number of Centers, Companies and organizations, both in Mexico and abroad. This methodology has been shared also with National Metrology Institutes of the Interamerican Metrology System (SIM), and has been adopted to some extent by Jamaica, Uruguay, Panama and Colombia [3]. There, an initiative emerged from a private metrology laboratory, Global Metric, to merge the MESURA approach with the productive metrology approach of Kunzmann and Pfeiffer [4]. This approach identifies loses or leaks of profit due to non-optimum metrological practices. It takes into account, as MESURA did, the Taguchi Loss Function [5], and the works of Mader, et al; Rodriguez, et al; Trejo, et al; Usuda, et al and Pendrill [6, 7, 8, 9, 10]. From the combination of these ideas, the purpose has been to analyse key processes in a company, identify opportunities for improvement with metrology and elaborate plans for Metrology Investment Projects (MIP). These MIP should evaluate clearly the technical opportunity to be addressed and translate it into economical data so that could be evaluated as any other investment project in terms of the Return on Investment (ROI) [11], Net Present Value (NPV) [12] or else. The methodology has been also seen as a complement to other improvement techniques as the Theory of Constrictions [13, 14], Re-Engineering [15], Lean Manufacturing [16, 17, 18, 19] and Six Sigma [20, 21]. The paper presents the developed methodology and the synergetic connections of MIP with other improvement philosophies, methodologies and techniques.
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Coletta, Nancy J., and Lori A. Maggisano. "Tolerance to Defocus at Low Spatial Frequencies: Effect of Luminance." In Vision Science and its Applications. Optica Publishing Group, 1998. http://dx.doi.org/10.1364/vsia.1998.sae.9.
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The effects of optical defocus on spatial contrast sensitivity are frequency dependent: defocus is detrimental to the visibility of high spatial frequencies, while low spatial frequency sensitivity is relatively less affected by the eye’s refractive state (Charman, 1979; Green and Campbell, 1965; Tucker, Charman and Ward, 1986). One would expect that vision at low luminance levels would be relatively unaffected by defocus, because the range of visible patterns is limited to lower spatial frequencies. However, Bedell (1986) reported that the contrast sensitivity loss produced by +1.25 D of defocus extended to lower spatial frequencies when the luminance was reduced. Similarly, the eye’s optical quality has a greater effect on low frequency sensitivity at low luminance than at high luminance levels (Coletta and Sharma, 1994). Experiments with acuity targets of fixed contrast also imply a decrease in tolerance to defocus at low luminance (Simpson, et al., 1986). Tucker and Charman (1986) measured acuity for gratings of 80% modulation as a function of focus and found that the through-focus acuity functions became narrower at mesopic luminance, even though the acuity limits shifted to lower spatial frequencies.
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Siegele, Dieter, Igor Varfolomeyev, and Gerhard Nagel. "Constraint Based Assessment of Postulated Nozzle Corner Cracks." In ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1352.
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Brittle failure for reactor pressure vessels (RPV) under loss of coolant accidents (LOCA) considering strip and plume cooling show the nozzle corner as leading region in load level (e.g. Siegele et al., 1999). For such transients postulated nozzle corner cracks are also leading in crack driving force compared to the fracture toughness of the material. On the other hand, the crack tip constraint and consequently the failure probability is reduced by yielding caused by high thermal stresses and in addition by the crack size being small relative to the bulk of the flange material. Under these conditions, the flaw assessment in the nozzle corner using fracture toughness data obtained on standard specimens with high constraint level is over-conservative. In this situation it is suitable to introduce the loss of crack tip constraint into the brittle failure analysis of the nozzle corner. This investigation focuses on the assessment of surface cracks in the nozzle corner of an RPV. Using the finite element method temperature and stress calculations are carried out for a postulated LOCA event. For crack postulates in the nozzle corner of various size and geometry in the nozzle corner, crack driving parameters (such as the J-integral and the stress intensity factor) are determined as functions of the crack tip temperature. To account for the crack tip constraint, the T-stress is then evaluated and used along with the master curve approach as suggested by Wallin (2001). Significant loss of constraint is found for the nozzle corner resulting in a large shift of the fracture toughness curve to lower temperatures, thus excluding initiation of the crack postulates.
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Salimzadeh, S., D. Kasperczyk, and T. Kadeethum. "Predicting Ground Surface Deformation Induced by Pressurized Fractures Using Conditional Generative Adversarial Networks." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0218.
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ABSTRACT Hydraulic fracturing has been widely applied in subsurface to facilitate hydrocarbon flow or as a preconditioning method to promote normal caving behavior in mining operations. The success of the method prominently relies on the geometry of the induced fractures in the host rock. An array of high-resolution tiltmeters is commonly used to measure the displacement gradient (tilt angle) of ground surface during hydraulic fracturing operation, and to infer the geometry of the induced fractures. In this work, we present a machine-learned model that is capable of predicting the surface tilt resulting from a pressurized fracture, using Conditional Generative Adversarial Networks (cGAN). Fracture apertures along horizontal and vertical planes are given as input while surface tilt vectors are provided as output for the forward model. A 3D finite element model with discrete fractures is utilized as the Full Order Model (FOM) to create training data. The fractures are pressurized uniformly to induce a displacement at the ground surface. Images of the fracture aperture in XY and XZ planes, and surface tilt vector components (tilt X and tilt Y) are used for the training process. Three different loss functions are used, and the predicted tilts are compared to the real (FOM) tilts. The results show that the trained cGAN with Wasserstein loss and gradient penalty (W-model) can predict the ground surface tilt due to the pressurized fractures at variable dip angles. INTRODUCTION Hydraulic fracturing has been frequently applied as a preconditioning method to promote normal caving behavior in mining operations. The success of the method prominently relies on the geometry of the induced fractures in the stiff overburden layer. An array of high-resolution tiltmeters is commonly used to measure the displacement gradient (tilt angle) of ground surface during hydraulic fracturing operation, and to infer the geometry of the induced fractures or pressure plumes using simplified models (Lecampion et al., 2005; Salimzadeh et al., 2022).
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Greenstein, Vivienne C., and Donald C. Hood. "A Test of the Decreased Responsiveness Hypothesis in Retinitis Pigmentosa." In Noninvasive Assessment of Visual Function. Optica Publishing Group, 1985. http://dx.doi.org/10.1364/navf.1985.tua2.
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The most fundamental deficit attributable to retinal disease is a reduction in sensitivity to light. Recently we suggested a simple physiological basis for this sensitivity loss (Hood and Greenstein, 1982, Greenstein et al., 1982.). Based upon psychophysical experiments performed on patients with a variety of retinal diseases we hypothesized that in the diseased retina all retinal cells are less responsive to light. That is because of anoxia, or decreased metabolic activity, or some other factor, retinal cells respond to all light intensities with a fraction of the response produced in a non-diseased retina. In fact, much of our data suggest that a simple form of this explanation can be applied to the retinal diseases we studied. It is not surprising that decreased cellular responsiveness occurs in a disease like diabetic retinopathy; it is surprising that the loss in foveal sensitivity found in a group of patients with retinitis pigmentosa (RP) was consistent with this explanation (Greenstein et al. 1984). If sensitivity loss in RP can be attributed entirely to decreased responsiveness then the effects of adding adapting lights are quantitatively predictable. In this paper this hypothesis is tested by collecting foveal data at two levels of steady adaptation on a selected group of RP patients.
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Raslan, Mohammed Samir, Anuj Gupta, Harun Ates, and Kristian Jessen. "A Two-Phase Transfer Function for Simulation of Fractured Ultratight Gas-Condensate Reservoirs." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213205-ms.
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Abstract In modeling of fractured ultratight gas-condensate reservoirs it is particularly important to represent liquid dropout, and its impact on fluid flow behavior, accurately. This, in turn, allows for design and optimization of reservoir production strategies, to mitigate potential production loss below the dewpoint pressure. Unfortunately, the traditional transfer functions used to describe the mass transfer between matrix/fracture segments in dual-porosity models (DPM’s) do not explicitly represent the complex physics of the inherent multiphase problem, which may complicate the application of existing simulators. Therefore, the objective of this work is to develop a two-phase transfer function that improves the modeling of gas-condensate systems via a DP representation. Commercial simulators typically offer a simple matrix/fracture mass transfer model to perform calculations in DP systems: The default shape factors are based on a pseudo-steady state (PSS) approximation, and for multiphase problems, the transfer function of Kazemi et al. (1976) is commonly used. Without sub-gridding, the traditional transfer functions cannot represent the extended transient behavior observed in ultratight fractured reservoirs. Furthermore, in compositional modeling of gas-condensate reservoirs, the averaging of matrix block properties masks the compositional changes near the matrix/fracture interface, that is critical to prediction of production behavior below the dewpoint. To overcome the limitations of the current models, we introduce a new transfer function that includes 1) a time-dependent shape factor and 2) a modified representation of the two-phase flow. We utilize the correction factor introduced by Zhang et al. (2022) allowing the shape factors to vary with time. For two-phase problems, instead of evaluating the mass transfer at an average pressure and composition, we propose a novel approach that evaluates the transfer function at conditions that reflect/approximate the pressure and composition/saturation gradients within the matrix block. By approximating the fluid state near the matrix/fracture interface, we represent the liquid buildup that dictates the fluid mobility more accurately. The open-source MATLAB Reservoir Simulation Toolbox (MRST) was used as a platform for the work presented in this paper: The existing single-porosity (SP) compositional model of MRST was first extended and validated (with the analytical solution for the single-phase pressure diffusion equation) to allow for DP modeling and simulation of condensate systems. We present calculation results for a single-block DPM, representative of a fractured ultratight gas-condensate reservoir, to demonstrate the limitations of the traditional mass transfer modeling approach. We then introduce the new transfer function and compare all calculation results with fine-grid SP reference models. In this work, we consider two condensate fluid descriptions: 1) a 4-component analog rich gas, and 2) a realistic 24-component fluid description from a gas-condensate reservoir. We demonstrate that the new transfer function represents the physical mechanisms at play more accurately and provides for a substantial improvement over the traditional formulation in terms of the amounts and compositions of the produced phases. The proposed method is motivated by the physics of the problem and requires no sub-gridding. The enhanced simulation of gas-condensate systems enables improved decision making in reservoir management and supports optimization of field development plans. In addition, the improved calculation of the surface streams, obtained from the new method, provides for a more accurate design of field surface facilities.
Reports on the topic "And Al-Bayyati's loss functions"
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Chamovitz, Daniel, and Albrecht Von Arnim. Translational regulation and light signal transduction in plants: the link between eIF3 and the COP9 signalosome. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7696515.bard.
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The COP9 signalosome (CSN) is an eight-subunit protein complex that is highly conserved among eukaryotes. Genetic analysis of the signalosome in the plant model species Arabidopsis thaliana has shown that the signalosome is a repressor of light dependent seedling development as mutant Arabidopsis seedlings that lack this complex develop in complete darkness as if exposed to light. These mutant plants die following the seedling stage, even when exposed to light, indicating that the COP9 signalosome also has a central role in the regulation of normal photomorphogenic development. The biochemical mode of action of the signalosome and its position in eukaryotic cell signaling pathways is a matter of controversy and ongoing investigation, and recent results place the CSN at the juncture of kinase signaling pathways and ubiquitin-mediated protein degradation. We have shown that one of the many CSN functions may relate to the regulation of translation through the interaction of the CSN with its related complex, eukaryotic initiation factor (eIF3). While we have established a physical connection between eIF3 subunits and CSN subunits, the physiological and developmental significance of this interaction is still unknown. In an effort to understand the biochemical activity of the signalosome, and its role in regulating translation, we originally proposed to dissect the contribution of "h" subunit of eIF3 (eIF3h) along the following specific aims: (i) Isolation and phenotypic characterization of an Arabidopsis loss-of-function allele for eIF3h from insertional mutagenesis libraries; (ii) Creation of designed gain and loss of function alleles for eIF3h on the basis of its nucleocytoplasmic distribution and its yeast-two-hybrid interactions with other eIF3 and signalosome partner proteins; (iii) Determining the contribution of eIF3h and its interaction with the signalosome by expressing specific mutants of eIF3h in the eIF3h- loss-of function background. During the course of the research, these goals were modified to include examining the genetic interaction between csn and eif3h mutations. More importantly, we extended our effort toward the genetic analysis of mutations in the eIF3e subunit, which also interacts with the CSN. Through the course of this research program we have made several critical scientific discoveries, all concerned with the apparent diametrically opposed roles of eIF3h and eIF3e. We showed that: 1) While eIF3e is essential for growth and development, eIF3h is not essential for growth or basal translation; 2) While eIF3e has a negative role in translational regulation, eIF3h is positively required for efficient translation of transcripts with complex 5' UTR sequences; 3) Over-accumulation of eIF3e and loss-of-function of eIF3h both lead to cop phenotypes in dark-grown seedlings. These results were published in one publication (Kim et al., Plant Cell 2004) and in a second manuscript currently in revision for Embo J. Are results have led to a paradigm shift in translation research – eIF3 is now viewed in all systems as a dynamic entity that contains regulatory subuits that affect translational efficiency. In the long-term agronomic outlook, the proposed research has implications that may be far reaching. Many important plant processes, including developmental and physiological responses to light, abiotic stress, photosynthate, and hormones operate in part by modulating protein translation [23, 24, 40, 75]. Translational regulation is slowly coming of age as a mechanism for regulating foreign gene expression in plants, beginning with translational enhancers [84, 85] and more recently, coordinating the expression of multiple transgenes using internal ribosome entry sites. Our contribution to understanding the molecular mode of action of a protein complex as fundamental as eIF3 is likely to lead to advances that will be applicable in the foreseeable future.
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Cobeen, Kelly, Vahid Mahdavifar, Tara Hutchinson, et al. Large-Component Seismic Testing for Existing and Retrofitted Single-Family Wood-Frame Dwellings (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, 2020. http://dx.doi.org/10.55461/hxyx5257.
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This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. Quantifying the difference of seismic performance of un-retrofitted and retrofitted single-family wood-frame houses has become increasingly important in California due to the high seismicity of the state. Inadequate lateral bracing of cripple walls and inadequate sill bolting are the primary reasons for damage to residential homes, even in the event of moderate earthquakes. Physical testing tasks were conducted by Working Group 4 (WG4), with testing carried out at the University of California San Diego (UCSD) and University of California Berkeley (UCB). The primary objectives of the testing were as follows: (1) development of descriptions of load-deflection behavior of components and connections for use by Working Group 5 in development of numerical modeling; and (2) collection of descriptions of damage at varying levels of peak transient drift for use by Working Group 6 in development of fragility functions. Both UCSD and UCB testing included companion specimens tested with and without retrofit. This report documents the portions of the WG4 testing conducted at UCB: two large-component cripple wall tests (Tests AL-1 and AL-2), one test of cripple wall load-path connections (Test B-1), and two tests of dwelling superstructure construction (Tests C-1 and C-2). Included in this report are details of specimen design and construction, instrumentation, loading protocols, test data, testing observations, discussion, and conclusions.
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Grumet, Rebecca, and Benjamin Raccah. Identification of Potyviral Domains Controlling Systemic Infection, Host Range and Aphid Transmission. United States Department of Agriculture, 2000. http://dx.doi.org/10.32747/2000.7695842.bard.
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Potyviruses form one of the largest and most economically important groups of plant viruses. Individual potyviruses and their isolates vary in symptom expression, host range, and ability to overcome host resistance genes. Understanding factors influencing these biological characteristics is of agricultural importance for epidemiology and deployment of resistance strategies. Cucurbit crops are subject to severe losses by several potyviruses including the highly aggressive and variable zucchini yellow mosaic virus (ZYMV). In this project we sought to investigate protein domains in ZYMV that influence systemic infection and host range. Particular emphasis was on coat protein (CP), because of known functions in both cell to cell and long distance movement, and helper component-protease (HC-Pro), which has been implicated to play a role in symptom development and long distance movement. These two genes are also essential for aphid mediated transmission, and domains that influence disease development may also influence transmissibility. The objectives of the approved BARD project were to test roles of specific domains in the CP and HC-Pro by making sequence alterations or switches between different isolates and viruses, and testing for infectivity, host range, and aphid transmissibility. These objectives were largely achieved as described below. Finally, we also initiated new research to identify host factors interacting with potyviral proteins and demonstrated interaction between the ZYMV RNA dependent RNA polymerase and host poly-(A)-binding protein (Wang et al., in press). The focus of the CP studies (MSU) was to investigate the role of the highly variable amino terminus (NT) in host range determination and systemic infection. Hybrid ZYMV infectious clones were produced by substituting the CP-NT of ZYMV with either the CP-NT from watermelon mosaic virus (overlapping, but broader host range) or tobacco etch virus (TEV) (non- overlapping host range) (Grumet et al., 2000; Ullah ct al., in prep). Although both hybrid viruses initially established systemic infection, indicating that even the non-cucurbit adapted TEV CP-NT could facilitate long distance transport in cucurbits, after approximately 4-6, the plants inoculated with the TEV-CPNT hybrid exhibited a distinct recovery of reduced symptoms, virus titer, and virus specific protection against secondary infection. These results suggest that the plant recognizes the presence of the TEV CP-NT, which has not been adapted to infection of cucurbits, and initiates defense responses. The CP-NT also appears to play a role in naturally occurring resistance conferred by the zym locus in the cucumber line 'Dina-1'. Patterns of virus accumulation indicated that expression of resistance is developmentally controlled and is due to a block in virus movement. Switches between the core and NT domains of ZYMV-NAA (does not cause veinal chlorosis on 'Dina-1'), and ZYMV-Ct (causes veinal chlorosis), indicated that the resistance response likely involves interaction with the CP-NT (Ullah and Grumet, submitted). At the Volcani Center the main thrust was to identify domains in the HC-Pro that affect symptom expression or aphid transmissibility. From the data reported in the first and second year report and in the attached publications (Peng et al. 1998; Kadouri et al. 1998; Raccah et al. 2000: it was shown that: 1. The mutation from PTK to PAK resulted in milder symptoms of the virus on squash, 2. Two mutations, PAK and ATK, resulted in total loss of helper activity, 3. It was established for the first time that the PTK domain is involved in binding of the HC-Pro to the potyvirus particle, and 4. Some of these experiments required greater amount of HC-Pro, therefore a simpler and more efficient purification method was developed based on Ni2+ resin.
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Cubides, A., D. Parra, R. Ortiz, et al. Effect of functional additives on the rumen development in the dairy calf. Corporación Colombiana de Investigación Agropecuaria - AGROSAVIA, 2016. http://dx.doi.org/10.21930/agrosavia.poster.2016.2.
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En los sistemas lácteos especializados, hay problemas debido al bajo desarrollo de la función del rumen de la pantorrilla, lo que causa un retraso en el comienzo de la vida productiva de los animales de reemplazo. El objetivo de este estudio fue evaluar la suplementación de aditivos funcionales en el desarrollo del rumen
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Kaffenberger, Michelle. Modeling the Long-Run Learning Impact of the COVID-19 Learning Shock: Actions to (More Than) Mitigate Loss. Research on Improving Systems of Education (RISE), 2020. http://dx.doi.org/10.35489/bsgrise-ri_2020/017.
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The COVID-19 pandemic has forced 1.7 billion children out of school temporarily. While many education systems are attempting varying degrees of remote learning, it is widely accepted that the closures will produce substantial losses in learning (World Bank, 2020; Kuhfeld et al., 2020). However, the real concern is not just that a few months of learning will be lost in the short run, but that these losses will accumulate into large and permanent learning losses as many children fall behind during school closures and never catch up. This note uses a calibrated model with a “pedagogical production function” (Kaffenberger and Pritchett, 2020) to estimate the potential long-term losses to children’s learning from the temporary shock of school closures. The model shows that without mitigation, children could lose more than a year’s worth of learning even from a three-month school closure as the short-term losses continue to compound after children return to school. Turning to mitigation strategies, the note examines the long-term effects of two strategies, finding that with some mitigation efforts education systems could come back from the crisis stronger than before.
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Barg, Rivka, Erich Grotewold, and Yechiam Salts. Regulation of Tomato Fruit Development by Interacting MYB Proteins. United States Department of Agriculture, 2012. http://dx.doi.org/10.32747/2012.7592647.bard.
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Background to the topic: Early tomato fruit development is executed via extensive cell divisions followed by cell expansion concomitantly with endoreduplication. The signals involved in activating the different modes of growth during fruit development are still inadequately understood. Addressing this developmental process, we identified SlFSM1 as a gene expressed specifically during the cell-division dependent stages of fruit development. SlFSM1 is the founder of a class of small plant specific proteins containing a divergent SANT/MYB domain (Barg et al 2005). Before initiating this project, we found that low ectopic over-expression (OEX) of SlFSM1 leads to a significant decrease in the final size of the cells in mature leaves and fruits, and the outer pericarp is substantially narrower, suggesting a role in determining cell size and shape. We also found the interacting partners of the Arabidopsis homologs of FSM1 (two, belonging to the same family), and cloned their tomato single homolog, which we named SlFSB1 (Fruit SANT/MYB–Binding1). SlFSB1 is a novel plant specific single MYB-like protein, which function was unknown. The present project aimed at elucidating the function and mode of action of these two single MYB proteins in regulating tomato fruit development. The specific objectives were: 1. Functional analysis of SlFSM1 and its interacting protein SlFSB1 in relation to fruit development. 2. Identification of the SlFSM1 and/or SlFSB1 cellular targets. The plan of work included: 1) Detailed phenotypic, histological and cellular analyses of plants ectopically expressing FSM1, and plants either ectopically over-expressing or silenced for FSB1. 2) Extensive SELEX analysis, which did not reveal any specific DNA target of SlFSM1 binding, hence the originally offered ChIP analysis was omitted. 3) Genome-wide transcriptional impact of gain- and loss- of SlFSM1 and SlFSB1 function by Affymetrix microarray analyses. This part is still in progress and therefore results are not reported, 4) Search for additional candidate partners of SlFSB1 revealed SlMYBI to be an alternative partner of FSB1, and 5) Study of the physical basis of the interaction between SlFSM1 and SlFSB1 and between FSB1 and MYBI. Major conclusions, solutions, achievements: We established that FSM1 negatively affects cell expansion, particularly of those cells with the highest potential to expand, such as the ones residing inner to the vascular bundles in the fruit pericarp. On the other hand, FSB1 which is expressed throughout fruit development acts as a positive regulator of cell expansion. It was also established that besides interacting with FSM1, FSB1 interacts also with the transcription factor MYBI, and that the formation of the FSB1-MYBI complex is competed by FSM1, which recognizes in FSB1 the same region as MYBI does. Based on these findings a model was developed explaining the role of this novel network of the three different MYB containing proteins FSM1/FSB1/MYBI in the control of tomato cell expansion, particularly during fruit development. In short, during early stages of fruit development (Phase II), the formation of the FSM1-FSB1 complex serves to restrict the expansion of the cells with the greatest expansion potential, those non-dividing cells residing in the inner mesocarp layers of the pericarp. Alternatively, during growth phase III, after transcription of FSM1 sharply declines, FSB1, possibly through complexing with the transcription factor MYBI serves as a positive regulator of the differential cell expansion which drives fruit enlargement during this phase. Additionally, a novel mechanism was revealed by which competing MYB-MYB interactions could participate in the control of gene expression. Implications, both scientific and agricultural: The demonstrated role of the FSM1/FSB1/MYBI complex in controlling differential cell growth in the developing tomato fruit highlights potential exploitations of these genes for improving fruit quality characteristics. Modulation of expression of these genes or their paralogs in other organs could serve to modify leaf and canopy architecture in various crops.
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Granot, David, Richard Amasino, and Avner Silber. Mutual effects of hexose phosphorylation enzymes and phosphorous on plant development. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7587223.bard.
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Research objectives 1) Analyze the combined effects of hexose phosphorylation and P level in tomato and Arabidopsis plants 2) Analyze the combined effects of hexose phosphorylation and P level in pho1 and pho2 Arabidopsis mutants 3) Clone and analyze the PHO2 gene 4) Select Arabidopsis mutants resistant to high and low P 5) Analyze the Arabidopsis mutants and clone the corresponding genes 6) Survey wild tomato species for growth characteristics at various P levels Background to the topic Hexose phosphorylating enzymes, the first enzymes of sugar metabolism, regulate key processes in plants such as photosynthesis, growth, senescence and vascular transport. We have previously discovered that hexose phosphorylating enzymes might regulate these processes as a function of phosphorous (P) concentration, and might accelerate acquisition of P, one of the most limiting nutrients in the soil. These discoveries have opened new avenues to gain fundamental knowledge about the relationship between P, sugar phosphorylation and plant development. Since both hexose phosphorylating enzymes and P levels affect plant development, their interaction is of major importance for agriculture. Due to the acceleration of senescence caused by the combined effects of hexose phosphorylation and P concentration, traits affecting P uptake may have been lost in the course of cultivation in which fertilization with relatively high P (30 mg/L) are commonly used. We therefore intended to survey wild tomato species for high P-acquisition at low P soil levels. Genetic resources with high P-acquisition will serve not only to generate a segregating population to map the trait and clone the gene, but will also provide a means to follow the trait in classical breeding programs. This approach could potentially be applicable for other crops as well. Major conclusions, solutions, achievements Our results confirm the mutual effect of hexose phosphorylating enzymes and P level on plant development. Two major aspects of this mutual effect arose. One is related to P toxicity in which HXK seems to play a major role, and the second is related to the effect of HXK on P concentration in the plant. Using tomato plants we demonstrated that high HXK activity increased leaf P concentration, and induced P toxicity when leaf P concentration increases above a certain high level. These results further support our prediction that the desired trait of high-P acquisition might have been lost in the course of cultivation and might exist in wild species. Indeed, in a survey of wild species we identified tomato species that acquired P and performed better at low P (in the irrigation water) compared to the cultivated Lycopersicon esculentum species. The connection between hexose phosphorylation and P toxicity has also been shown with the P sensitive species VerticordiaplumosaL . in which P toxicity is manifested by accelerated senescence (Silber et al., 2003). In a previous work we uncovered the phenomenon of sugar induced cell death (SICD) in yeast cells. Subsequently we showed that SICD is dependent on the rate of hexose phosphorylation as determined by Arabidopsis thaliana hexokinase. In this study we have shown that hexokinase dependent SICD has many characteristics of programmed cell death (PCD) (Granot et al., 2003). High hexokinase activity accelerates senescence (a PCD process) of tomato plants, which is further enhanced by high P. Hence, hexokinase mediated PCD might be a general phenomena. Botrytis cinerea is a non-specific, necrotrophic pathogen that attacks many plant species, including tomato. Senescing leaves are particularly susceptible to B. cinerea infection and delaying leaf senescence might reduce this susceptibility. It has been suggested that B. cinerea’s mode of action may be based on induction of precocious senescence. Using tomato plants developed in the course of the preceding BARD grant (IS 2894-97) and characterized throughout this research (Swartzberg et al., 2006), we have shown that B. cinerea indeed induces senescence and is inhibited by autoregulated production of cytokinin (Swartzberg et al., submitted). To further determine how hexokinase mediates sugar effects we have analyzed tomato plants that express Arabidopsis HXK1 (AtHXK1) grown at different P levels in the irrigation water. We found that Arabidopsis hexokinase mediates sugar signalling in tomato plants independently of hexose phosphate (Kandel-Kfir et al., submitted). To study which hexokinase is involved in sugar sensing we searched and identified two additional HXK genes in tomato plants (Kandel-Kfir et al., 2006). Tomato plants have two different hexose phosphorylating enzymes; hexokinases (HXKs) that can phosphorylate either glucose or fructose, and fructokinases (FRKs) that specifically phosphorylate fructose. To complete the search for genes encoding hexose phosphorylating enzymes we identified a forth fructokinase gene (FRK) (German et al., 2004). The intracellular localization of the four tomato HXK and four FRK enzymes has been determined using GFP fusion analysis in tobacco protoplasts (Kandel-Kfir et al., 2006; Hilla-Weissler et al., 2006). One of the HXK isozymes and one of the FRK isozymes are located within plastids. The other three HXK isozymes are associated with the mitochondria while the other three FRK isozymes are dispersed in the cytosol. We concluded that HXK and FRK are spatially separated in plant cytoplasm and accordingly might play different metabolic and perhaps signalling roles. We have started to analyze the role of the various HXK and FRK genes in plant development. So far we found that LeFRK2 is required for xylem development (German et al., 2003). Irrigation with different P levels had no effect on the phenotype of LeFRK2 antisense plants. In the course of this research we developed a rapid method for the analysis of zygosity in transgenic plants (German et al., 2003).
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Hodges, Thomas K., and David Gidoni. Regulated Expression of Yeast FLP Recombinase in Plant Cells. United States Department of Agriculture, 2000. http://dx.doi.org/10.32747/2000.7574341.bard.
Full textAbstract:
Research activities in both our laboratories were directed toward development of control of the FLP/frt recombination system for plants. As described in the text of the research proposal, the US lab has been engaged in developing regulatory strategies such as tissue-specific promoters and the steroid-inducible activation of the FLP enzyme while the main research activities in Israel have been directed toward the development and testing of a copper-regulated expression of flp recombinase in tobacco (this is an example of a promoter activation by metal ions). The Israeli lab hat additionally completed experiments of previous studies regarding factors affecting the efficiency of recombinase activity using both a gain-of-function assay (excisional-activation of a gusA marker) and loss of function assay (excision of a rolC marker) in tobacco. Site-specific recombinase systems, in particular the FLP/frt and R/RS systems of yeast and the Cre/lox system of bacteriophage P1, have become an essential component of targeted genetic transformation procedures both in animal and plant organisms. To provide more flexibility in transgene excisions by the recombinase systems as well as gene targeting, and to widen possible applications, the development of controlled or regulated recombination systems is highly desirable and was therefore the subject of this research proposal. There are a few possible mechanisms to regulate expression of a recombinase system. They include: 1) control of the recombination system by having the target sites (e.g. frt) in one plant and the flp recombinase gene in another, and bringing the two together by cross fertilization. 2) regulation of promoter activities by external stimuli such as temperature, chemicals, metal ions, etc. 3) regulation of promoter activities by internal signals, i.e. cell- or tissue-specific, or developmental regulation. 4) regulation of enzyme activity by providing cofactors essential for biochemical reactions to take place such as steroid molecules in conjunction with a steroid ligand-binding protein (domains). During the course of this research our major emphasis have been focused toward studying the feasibility of hybrid seed production in Arabidopsis, using FLP/frt. Male-sterility was induced using the antisence of a pollen- and tapetum-specific gene, bcp1, isolated from Arabidopsis. The sterility inducing gene was flanked by frt sites. Upon cross pollination of flowers of male-sterile plants with pollen from FLP-containing plants, viable seeds were produced, and the progeny hybrid plants developed normally. The major achievement from this work is the first demonstration of using a site-specific recombinase to restore fertility in male-sterile plants (see attached paper, Luo et al., Plant J 2000; 23:423-430). The implication from this finding is that site-specific recombination systems can be applied in crop plants as a useful alternative method for hybrid seed production.