Search

Parametric rolling is a parametric excitation phenomenon caused by GM variation in waves. There are a lot of studies of the estimation the conditions, the occurrence, and the amplitude of parametric rolling. On the other hand, there are relatively few cases in which theoretical methods for estimating parametric roll amplitudes in irregular waves have been validated in tank tests. The primary objective of this study is to validate theoretical estimation methods for the parametric roll amplitude in irregular waves and improve their accuracy. First, the probability density functions (PDF) of the parametric roll amplitude obtained from the model ship motion experiment in irregular waves are compared with that obtained from theoretical estimation methods. Second, the method to improve the accuracy of estimation of the roll restoring variation in irregular waves is suggested. Third, the method to estimate the distribution of the maximum amplitude of parametric rolling in irregular waves. As a result, the PDFs of the roll amplitude obtained from the experiments differ from the results of theoretical estimation. After that, by correcting GM variation, the results of theoretical estimation are closer to the experimental results. Moreover, by the theoretical estimation method using the moment equation, the qualitative estimation for the PDF of the maximum roll amplitude is succeeded., Comment: 12 pages, 23 figures, This paper is under review now by JMST(Journal of Marine Science and Technology)

The broaching that follows the surf-riding is a dangerous phenomenon that can lead to the capsizing of a vessel due to its violent yaw motion. Most of the previous studies on surf-riding phenomena in irregular waves have been conducted by replacing irregular waves with regular waves. In contrast, this study provides suggestions on how to directly calculate nonlinear surge motion in irregular seas. In this study, the statistical aspects of the surf-riding phenomenon are first presented. Then, under several approximations, we show how to calculate the probability density function theoretically. Although the results obtained are based on strong approximations, it is found that the nonlinear surge oscillations in irregular following seas can be explained from a qualitative point of view.

In clinical practice, we often see significant delays between MRI scans and the diagnosis made by radiologists, even for severe cases. In some cases, this may be caused by the lack of additional information and clues, so even the severe cases need to wait in the queue for diagnosis. This can be avoided if there is an automatic software tool, which would supplement additional information, alerting radiologists that the particular patient may be a severe case. We are presenting an automatic brain MRI Screening Tool and we are demonstrating its capabilities for detecting tumor-like pathologies. It is the first version on the path toward a robust multi-pathology screening solution. The tool supports Federated Learning, so multiple institutions may contribute to the model without disclosing their private data., Comment: 5 pages, 2 figures. Submitted to ISBI 2024 conference

Ion acceleration from gaseous targets driven by relativistic-intensity lasers was demonstrated as early as the late 90s, yet most of the experiments conducted to date have involved picosecond-duration, Nd:glass lasers operating at low repetition rate. Here, we present measurements on the interaction of ultraintense ($\sim 10^{20}\,\rm W\,cm^{-2}$, 1 PW), ultrashort ($\sim 70\,\rm fs$) Ti:Sa laser pulses with near-critical ($\sim 10^{20}\,\rm cm^{-3}$) helium gas jets, a debris-free targetry compatible with high ($\sim 1\,\rm Hz$) repetition rate operation. We provide evidence of $\alpha$ particles being forward accelerated up to $\sim 2.7\,\rm MeV$ energy with a total flux of $\sim 10^{11}\,\rm sr^{-1}$ as integrated over $>0.1 \,\rm MeV$ energies and detected within a $0.5\,\rm mrad$ solid angle. We also report on on-axis emission of relativistic electrons with an exponentially decaying spectrum characterized by a $\sim 10\,\rm MeV$ slope, i.e., five times larger than the standard ponderomotive scaling. The total charge of these electrons with energy above 2 MeV is estimated to be of $\sim 1 \,\rm nC$, corresponding to $\sim 0.1\,\%$ of the laser drive energy. In addition, we observe the formation of a plasma channel, extending longitudinally across the gas density maximum and expanding radially with time. These results are well captured by large-scale particle-in-cell simulations, which reveal that the detected fast ions most likely originate from reflection off the rapidly expanding channel walls. The latter process is predicted to yield ion energies in the MeV range, which compare well with the measurements. Finally, direct laser acceleration is shown to be the dominant mechanism behind the observed electron energization.

Writing is an essential element of literacy development, and language plays a central role in the composing process, including developing, organizing, and refining ideas. Language and writing are interconnected, making it paramount for educators to attend to the development of deaf students' language skills. In this quasi-experimental study, we examined the impact of strategic and interactive pedagogical approaches, namely Strategic and Interactive Writing Instruction (SIWI), implemented with deaf students in grades 3-6 to develop genre-specific traits in their expressive language (spoken or signed) and writing. In this study, a total of 16 teachers and their 69 students participated in the treatment and comparison groups. Expressive language and writing samples were collected at the beginning and end of the year for three different genres. Students in the treatment group showed statistically significant gains in their expressive and written language for recount and information genres when compared to students in the comparison group. There was not a significant treatment effect on persuasive expressive language or writing. Additionally, there was a significant positive correlation between expressive language and writing at both time points across all three genres. This study provides evidence on the importance of attending to language skills during literacy instruction. [This paper was published in "Journal of Deaf Studies and Deaf Education" v29 n3 p350-361 2024.]

Numerous accidents caused by parametric rolling have been reported on container ships and pure car carriers (PCCs). A number of theoretical studies have been performed to estimate the occurrence condition of parametric rolling in both regular and irregular seas. Some studies in random wave conditions have been the approximate extension of the occurrence conditions for regular waves (e.g. Maki et al). Furthermore, several researches have been based on the stochastic process in ocean engineering (Roberts and Dostal). This study tackled the parametric rolling in irregular seas from the stability of the system's origin. It provided a novel theoretical explanation of the instability mechanism for two cases: white noise parametric excitation and colored noise parametric excitation. The authors then confirmed the usefulness of the previously provided formulae by Roberts and Dostal through numerical examples., Comment: 10 pages, 4 figures

We characterize strongly finitary monads on categories $\mathsf{Pos}$, $\mathsf{CPO}$ and $\mathsf{DCPO}$ as precisely those preserving sifted colimits. Or, equivalently, enriched finitary monads preserving reflexive coinserters. We study sifted colimits in general enriched categories. For $\mathsf{CPO}$ and $\mathsf{DCPO}$ we characterize varieties of continuous algebras as precisely the monadic categories for strongly finitary monads.

Quantitative algebras are algebras enriched in the category $\mathsf{Met}$ of metric spaces so that all operations are nonexpanding. Mardare, Plotkin and Panangaden introduced varieties (aka $1$-basic varieties) as classes of quantitative algebras presented by quantitative equations. We prove that they bijectively correspond to strongly finitary monads $T$ on $\mathsf{Met}$. This means that $T$ is the Kan extension of its restriction to finite discrete spaces. An analogous result holds in the category $\mathsf{CMet}$ of complete metric spaces. Analogously, continuous algebras are algebras enriched in $\mathsf{CPO}$, the category of $\omega$-cpos, so that all operations are continuous. We introduce equations between extended terms, and prove that varieties (classes presented by such equations) correspond bijectively to strongly finitary monads $T$ on $\mathsf{CPO}$. This means that $T$ is the Kan extension of its restriction to finite discrete cpos. (The two results have substantially different proofs.) An analogous result is also presented for monads on $\mathsf{DCPO}$. We also characterize strong finitarity in all the categories above by preservations of certain weighted colimits. As a byproduct we prove that directed colimits commute with finite products in all cartesian closed categories.

Quantitative algebras are $\Sigma$-algebras acting on metric spaces, where operations are nonexpanding. Mardare, Panangaden and Plotkin introduced 1-basic varieties as categories of quantitative algebras presented by quantitative equations. We prove that for the category $\mathsf{UMet}$ of ultrametric spaces such varieties bijectively correspond to strongly finitary monads on $\mathsf{UMet}$. The same holds for the category $\mathsf{Met}$ of metric spaces, provided that strongly finitary endofunctors are closed under composition. For uncountable cardinals $\lambda$ there is an analogous bijection between varieties of $\lambda$-ary quantitative algebras and monads that are strongly $\lambda$-accessible. Moreover, we present a bijective correspondence between $\lambda$-basic varieties as introduced by Mardare et al and enriched, surjections-preserving $\lambda$-accesible monads on $\mathsf{Met}$. Finally, for general enriched $\lambda$-accessible monads on $\mathsf{Met}$ a bijective correspondence to generalized varieties is presented.

Container ships encounter large roll angles and high acceleration, and container loss remains a problem. This study proposes a method for calculating the probability density function~(PDF) of roll angular and cargo lateral accelerations. First, the moment values of these accelerations are derived using the linearity of expectation and the validity of this method is examined. Second, the PDF shapes of these accelerations are proposed and their coefficients are determined using the obtained moment values. Our proposed method can be used to derive the PDFs of roll angular and cargo lateral accelerations., Comment: 9 pages, 8 figures, preprint

The RF plasma slit jet, which produces 150 mm wide streaming plasma outside the jet body, exhibits exciting self-organization phenomena that resemble the self-organized patterns of dielectric barrier discharge (DBD) filaments. Similarly, as in DBD, the filaments are surrounded by an inhibition zone that does not allow two filaments to come closer to each other. With fast camera imaging, we observed the filamentary character of the discharge in all the studied gas feeds (Ar, Ar/N$_2$, and Ar/O$_2$). Still, the visual appearance of the filaments in the plasma and their interaction with a dielectric surface depended significantly on the gas feed. As the breakdown voltage in pure Ar is relatively low compared to the applied one, new filaments form frequently. Such newly created filaments disrupted the characteristic inter-filament distance, forcing the system to rearrange. The frequent ignition and decay processes in Ar led to short filament lifetimes (0.020-0.035 s) and their high jitter speed (0.9-1.7 m/s), as determined with an image processing custom code based on Gwyddion libraries. The number of filaments was lower in the Ar/O$_2$ and Ar/N$_2$ mixtures. It was attributed to a loss of energy in the excitation of rotational and vibrational levels and oxygen electronegativity. Since the probability of low-current side discharges transitioning into the full plasma filaments was limited in the gas mixtures, the self-organized pattern was seldom disrupted, leading to lesser movement and longer lifetimes. Unlike in Ar or Ar/O$_2$, the constricted filaments in Ar/N$_2$ were surrounded by diffuse plasma plumes, likely connected to the presence of long-lived nitrogen species. We demonstrated in the polypropylene treatment that the self-organization phenomena affected the treatment uniformity., Comment: 19 pages, 11 figures, submitted to Plasma Sources Science and Technology

Radiative shocks (RS) are complex phenomena which are ubiquitous in astrophysical environments. The study of such hypersonic shocks in the laboratory, under controlled conditions, is of primary interest to understand the physics at play and also to check the ability of numerical simulations to reproduce the experimental results. In this context, we conducted, at the Prague Asterix Laser System facility (PALS), the first experiments dedicated to the study of two counter-propagating radiative shocks propagating at non-equal speeds up to 25-50 km/s in noble gases at pressures ranging between 0.1 and 0.6 bar. These experiments highlighted the interaction between the two radiative precursors. This interaction is qualitatively but not quantitatively described by 1D simulations. Preliminary results obtained with XUV spectroscopy leading to the estimation of shock temperature and ion charge of the plasma are also presented.

Although machine learning (ML) has shown promise in numerous domains, there are concerns about generalizability to out-of-sample data. This is currently addressed by centrally sharing ample, and importantly diverse, data from multiple sites. However, such centralization is challenging to scale (or even not feasible) due to various limitations. Federated ML (FL) provides an alternative to train accurate and generalizable ML models, by only sharing numerical model updates. Here we present findings from the largest FL study to-date, involving data from 71 healthcare institutions across 6 continents, to generate an automatic tumor boundary detector for the rare disease of glioblastoma, utilizing the largest dataset of such patients ever used in the literature (25,256 MRI scans from 6,314 patients). We demonstrate a 33% improvement over a publicly trained model to delineate the surgically targetable tumor, and 23% improvement over the tumor's entire extent. We anticipate our study to: 1) enable more studies in healthcare informed by large and diverse data, ensuring meaningful results for rare diseases and underrepresented populations, 2) facilitate further quantitative analyses for glioblastoma via performance optimization of our consensus model for eventual public release, and 3) demonstrate the effectiveness of FL at such scale and task complexity as a paradigm shift for multi-site collaborations, alleviating the need for data sharing., Comment: federated learning, deep learning, convolutional neural network, segmentation, brain tumor, glioma, glioblastoma, FeTS, BraTS

Forty-four elementary grade teachers of deaf and hard of hearing students were surveyed about how they taught writing and their beliefs about writing. Beliefs about writing included their self-efficacy to teach writing, attitude towards writing, and epistemological beliefs about writing. These teachers from 15 different states in the United States slightly agreed they were efficacious writing teachers and they were slightly positive about their writing. They slightly agreed that learning to write involves effort and process, moderately disagreed that writing development is innate or fixed, slightly disagreed that knowledge about writing is certain, and were equally split about whether writing knowledge comes from authorities and experts. On average, teachers applied the 22 instructional writing practices surveyed at least once a month. They reported their students wrote weekly, and their writing was supported through goal setting, feedback, and prewriting activities. Writing instruction mostly focuses on teaching grammar and how to plan compositions. Teacher self-efficacy uniquely and statistically predicted reported teaching practices after attitude towards writing and epistemological beliefs were first controlled. Recommendations for future research and implications for practice are presented. [This paper was published in "Journal of Deaf Studies and Deaf Education" v26 n3 p438-450 2021.]

Literacy intervention research tests our best ideas about instruction and forges a pathway forward toward deeper and more nuanced understandings of how children think, communicate, and learn. This chapter describes the components of the development of literacy interventions, explaining how to construct and evaluate each component in sequence to generate robust, reliable evidence for practice. In doing so, the chapter discusses some of the specific contexts of, and challenges for, literacy intervention research in deaf education. In order to illustrate important considerations for designing and interpreting literacy intervention studies in this context, two case studies of interventions developed or applied with deaf and hard-of-hearing children are included. [This chapter was published in S. R. Easterbrooks and H. M. Dostal (Eds.), "The Oxford Handbook of Deaf Studies in Literacy." Oxford, UK: Oxford University Press.]

We present a toy model of opinion spreading in a society which combines a self-reinforcing mechanism with diffusion. The relative strength of these two mechanisms - called the affectability of the system - is a free parameter of the model. The model is run on a scale-free network and its asymptotic behaviour is investigated. A surprising emergent effect is observed: If every individual becomes more attentive to the opinions of others, the society as a whole switches from a plurality of nuanced opinions into the state of an absolute consensus on an extreme opinion. This counter-intuitive emergent behaviour may help to explain certain paradoxes in human history., Comment: 7 pages, 4 figures, done with high school students

Parametric rolling is one of the dangerous dynamic phenomena. In order to discuss the safety of a vessel when a dangerous phenomenon occurs, it is important to estimate the probability of certain dynamical behavior of the ship with respect to a certain threshold level. In this paper, the moment values are obtained by solving the moment equations. Since the stochastic differential equation(SDE) is needed to obtain the moment equations, the Autoregressive Moving Average(ARMA) filter is used. The effective wave is modeled by using the 6th-order ARMA filter. In addition, the parametric excitation process is modeled by using a non-memory transformation obtained from the relationship between GM and wave elevation. The resulting system of equations is represented by the 8th-order It\^o stochastic differential equation, which consists of a second-order SDE for the ship motion and a 6th-order SDE for the effective wave. This system has nonlinear components. Therefore, the cumulant neglect closure method is used as higher-order moments need to be truncated. Furthermore, the probability density function of roll angle is determined by using moment values obtained from the SDE and the moment equation. Here, two types of the probability density function are suggested and have a good agreement., Comment: preprint, 13 pages, 14 figures. accepted (Journal of Marine Science and Technology)

This study explores the intertwined phenomena of language deprivation, emergent writing, and translanguaging in deaf students without additional disabilities in grades 3-6. A case study was conducted using deductive and inductive approaches to analyze 42 writing samples. There were four areas of focus: (1) stages of emergent writing development; (2) writing change over time; (3) emerging writing and translanguaging features; and (4) writing features unique to the context of language deprivation. First, pre-writing samples add to evidence that older deaf students undergo similar developmental processes with their emergent writing patterns. Second, an analysis of pre- and post-writing samples indicated that movement between stages occurred for most students. Third, students incorporated emergent writing and translanguaging features that reflected the application of their linguistic resources in writing. Finally, existing theories were extended by uncovering writing characteristics unique to the context of language deprivation. Incomplete ideation and restricted translanguaging practices were identified as attributions of language deprivation impacting cognitive and linguistic resources. This study provides evidence that deaf students as old as thirteen years old are developing emergent writing skills not because of their deafness but likely because they were in environments that produced chronic inadequate language access. [This paper was published in "Bilingual Research Journal."]

Writing teachers play an extraordinarily important role in their students' writing development. Teachers' motivational beliefs, such as attitudes toward writing, perceptions of their efficacy to teach writing, or preparation to use evidence-based instructional practices, impact their writing instruction, which directly affects the advancement of students' writing skills. Deaf writers are a subpopulation of writers who may face discriminatory beliefs toward their writing development stemming from ableism, audism, or linguicism. Deaf education teachers may doubt their abilities to teach bilingual/multilingual students or teach deaf students experiencing language deprivation. The current study investigates whether deaf education teachers' beliefs can be fostered through an intensive one-year professional development (PD) program designed specifically for deaf education teachers. In this randomized controlled trial, we examine the extent to which the participation of deaf education teachers in specialized PD and subsequent writing instruction implementation (n=26) impacts their pedagogical content "knowledge," use of evidence-based "practices" for teaching writing, "interest," "attitudes," "efficacy" in teaching writing, and "epistemological beliefs" about writing compared to teachers in a business as usual condition (n=24). Pre-post regression analyses indicate statistically significant group differences (with the treatment group scoring higher) on all variables except attitude and some epistemological beliefs. We speculate that specialized, sustained PD paired with supported implementation of writing instruction and ongoing teacher reflection are contributing factors to changes in teachers' motivational beliefs. [This paper was published in "Frontiers in Psychology" v14 2023.]

This study explores the impact of Strategic and Interactive Writing Instruction (SIWI) on six students' written language skills through the application of a multiple-baseline probe single case design with embedded condition. This was part of a larger Institute of Education Sciences (IES)-funded project focused on the development and feasibility of implementation of SIWI. For the majority of skills analyzed, there were improvements in the mean level of performance with the implementation of SIWI, as well as more consistent responding and positive trends in the data. The study also revealed that teachers are in need of additional tools to aid the systematic identification and tracking of syntax skills in children's written language development, and to distinguish these from other writing skills such as convention or handwriting. [This paper was published in "Journal of Deaf Studies and Deaf Education" v25 n2 p224-238 2020 (EJ1252378).]

Recent work on compositional distributional models shows that bialgebras over finite dimensional vector spaces can be applied to treat generalised quantifiers for natural language. That technique requires one to construct the vector space over powersets, and therefore is computationally costly. In this paper, we overcome this problem by considering fuzzy versions of quantifiers along the lines of Zadeh, within the category of many valued relations. We show that this category is a concrete instantiation of the compositional distributional model. We show that the semantics obtained in this model is equivalent to the semantics of the fuzzy quantifiers of Zadeh. As a result, we are now able to treat fuzzy quantification without requiring a powerset construction., Comment: https://link.springer.com/chapter/10.1007/978-3-030-53654-1_6