Critical Space Research Articles

Regional Coordinated Development in the Megacity Regions: Spatial Pattern and Driving Forces of the Guangzhou-Foshan Cross-Border Area in China

With globalization and informatization, cross-border areas have become increasingly critical interactive spaces, experiencing rapid development and extensive changes in residents’ cross-border travel, constantly changing the spatial patterns of neighboring cities. However, existing studies lack in-depth discussions of the new spatiotemporal characteristics of human activities, spatial pattern evolution, and the driving factors behind them. Therefore, taking the Guangzhou-Foshan metropolitan area as a case, this paper focus on the analysis of the cross-city travel of residents in these border areas in 2019, and investigated the evolution of spatial patterns and the driving forces in the border area during 1985–2020. We found that, instead of the previous one-way attraction pattern caused by the spread of residence, a large number of cross-city trips for leisure and entertainment purposes emerged, and the one-way unbalanced flow, “Foshan to Guangzhou”, changed to two-way circulation. We also explore the scenario in which the travel behavior of urban dwellers in these two cities considerably interacts with the effect of urban structure to produce the observed mobility patterns. Second, we determined the spatial pattern of the Guangzhou-Foshan region from 1985 to 2020 to be on of spreading expansion, with Liwan District as the central core, connecting to several sub-centers. The cross-border area in the Guangzhou-Foshan region represented a compact, extremely high degree of integration and a well-matched functional space. Third, driven by the forces stemming from the planning guidelines and the improving transportation network construction in the border area, the growth points of the two cities continued to expand toward the borderline regarding integrated development, while the growth axis was mainly in the direction of the city border, urban arterial roads, and subway lines. We concluded with development suggestions for increasing travel interactions and optimizing spatial patterns to build a common vision of the whole Guangzhou-Foshan pattern of integration.

In-situ three-dimensional investigation on micro ductile fracture mechanism of mild steel

In this paper, in-situ micro-computed tomography (micro-CT) experiments were performed on mild steel samples under monotonic tension using X-ray microscopy. A three-dimensional (3D) visualization model was reconstructed and the characteristics of void evolution under different strain states, such as void distribution, void shape, void growth and void coalescence, were quantitatively analyzed from a 3D perspective. It is found that void growth mainly depends on the stress state, while void coalescence is controlled by the stress state and intervoid spacing. The critical intervoid spacing for void coalescence occurring at the post-necking stage was given. Two stages of void coalescence, local coalescence and global coalescence, were found during void evolution. Local void coalescence was first observed at a strain of 10.02%, well before necking, but has a negligible effect on the overall void evolution. Global void coalescence was developed after the formation of a strain localization band dominated by large coalesced voids in the necking region. The propagation of fine cracks between voids along the strain localization band leads to the formation of macroscopic ductile cracks. Overall, the micro ductile fracture of mild steel is triggered by the combined effects of multiple damage mechanisms rather than independent competition.

Global Instability of Rod Eutectic Growth in Directional Solidification

In our previous work, we obtained the uniformly valid asymptotic solution of a cylindrical rod eutectic. In order to further study the critical point of the stable growth of a rod eutectic, we have considered the unsteady growth of a rod eutectic on the basis of the steady solution of the rod eutectic. Based on the experimental system of rod eutectic growth, combined with solidification thermodynamics and kinetics, the unsteady mathematical model of the rod eutectic was established. We used the asymptotic analysis method to seek the analytical solution of the mathematical model and used the nonlinear stability analysis theory to analyze the analytical solution and establish the corresponding disturbance model. We obtained the analytic form of the global mode solution and the corresponding quantization conditions and find that there is a stable growth mode, namely the mode (ST-mode), for rod eutectic growth; when ε<εST0, the rod eutectic growth is stable, when ε>εST0, the rod eutectic growth is unstable and when ε=εST0, the rod eutectic growth is of a neutral stability. The critical eutectic spacing of succinonitrile(D)camphor (SCN-DC) predicted by us is smaller than that predicted by Jackson–Hunt, which is consistent with the corresponding experimental data. Finally, we found that the critical eutectic spacing and stable region of rod eutectic growth changed little with the temperature gradient.

Disentangle irrelevant and critical representations for face anti-spoofing

Face recognition systems have been widely applied in security-related areas of our daily life. However, they are vulnerable to face spoofing attacks. Specifically, an attacker can fool a face recognition system into making false decisions, by presenting spoof face information (such as printed photos, replayed videos, etc.), rather than live face, to the face recognition system. Therefore, Face Anti-Spoofing (FAS) is critical for the security operation of a face recognition system.Deep learning-based FAS approaches show the best performance among existing FAS approaches. The basic idea of deep learning-based FAS approaches is to learn statistical representations capable of distinguishing spoof faces from live ones, and then leverage the learned representations for live and spoof face classifications. Therefore, the learned representations play a key role in the performance of FAS. However, most existing approaches learn representations from representation-entangled spaces, in which critical and irrelevant representations for live and spoof face classifications are entangled with each other, thereby bringing a negative influence on the performance of a FAS system.To address the issue, we introduced a Twin Autoencoder Disentanglement (TAD) framework. Our TAD framework utilizes adversarial learning and a reconstruction strategy to disentangle both critical and irrelevant representations into two mutually independent representation spaces. In addition, to further suppress irrelevant representations that may remain in the critical representation space, we design a multi-branch supervision architecture (MSA) and embed it into TAD. MSA achieves the goal via imposing depth supervision and pattern supervision to the critical representation space. i.e., learning spatial representation (face depth information) and texture representation (face spoof pattern information).Experimental results on four typical public datasets, OULU-NPU, SiW, Replay-Attack, and CASIA-MFSD, demonstrate that our proposed TAD approach successfully disentangles critical and irrelevant representations, and the two disentangled representations are more interpretable than state-of-the-art FAS methods. The codes are available at https://github.com/TAD-FAS/TAD.

ON THE REGULARITY CRITERION ON ONE VELOCITY COMPONENT FOR THE MICROPOLAR FLUID EQUATIONS

In this paper, we establish a regularity criterion for micropolar fluid flows in terms of the one component of the velocity in critical Morrey-Campanato space. More precisely, we show that if ...<∞, where 0<r<9/10 then the weak solution (u,w) is regular.

A Surgical Robotic Framework for Safe and Autonomous Data-Driven Learning and Manipulation of an Unknown Deformable Tissue with an Integrated Critical Space

Aside from reliable robotic hardware and sensing technologies, to successfully transition from teleoperation to an autonomous and safe minimally invasive robotic surgery on unknown Deformable Tissues (U-DTs), various challenges need to be simultaneously considered and tackled to ensure safety and accuracy of the procedure. These challenges mainly include but are not limited to online modeling and reliable tracking of a U-DT with integrated critical tissues as well as development of reliable and fast control algorithms to enable safe, accurate, and autonomous surgical procedures. To collectively and simultaneously address these challenges and toward performing an autonomous and safe minimally invasive robotic surgery in a confined environment, in this paper, we present a surgical robotic framework with (i) real-time vision-based detection algorithm based on a Convolutional Neural Network (CNN) architecture that enables tracking the time-varying deformation of a critical tissue located within a U-DT and (ii) a complementary data-driven adaptive constrained optimization approach that learns deformation behavior of a U-DT while autonomously manipulating it within a time-varying constrained environment defined based on the output of the CNN detection algorithm. To thoroughly evaluate the performance of the proposed framework, we used the da Vinci Research Kit (dVRK) and performed various experiments on a custom-designed U-DT phantom with an arbitrary deformable vessel embedded within the phantom’s body (serving as the U-DT’s integrated critical space). Various experiments were conducted and analyzed to demonstrate the performance of the proposed framework and ensure robustness and safety while performing an autonomous surgical procedure.

“There is a Fabulous Play in the House of Cards:” Gender and Memory-Mapping in the Film Tasher Ghawr

The pandemic's collective memory features large-scale destruction in the public and private realms. This paper studies the latter by speculating on the complex interrelationship between gender, media, and collective memory. By foregrounding the potential of fictional experientialities to engage with real-life phenomena, the paper analyzes the movie Tasher Ghawr as an epitome of women’s experience of the COVID-19 lockdown. This movie was selected pertaining to its current relevance. The paper undertakes a qualitative investigation through a textual analysis of the movie’s narrative. The researchers use theories such as collective memory, gender performativity, affect, and counter-memory to illustrate how the protagonist Sujatha’s individual gendered memory constantly constructs and deconstructs the collective memory of women as it pertains to the pandemic. The notion of collective memory is highlighted as complexly entangled and dialogically engaged with the memories of the individuals. This paper demonstrates this by constructing Sujatha as a subject defined by the norms embedded in the female collective memory and then shedding light on her subversive brilliance in questioning the stronghold of these discourses. This act of subversion produces a new strand of collective memory where women are no longer simply victims. The results of this study indicate that while women are constructed as subjects through collective memory processes, they also demonstrate a potential to subvert and question the stronghold of this collective memory that presupposes their submissiveness and servility. For future researchers, this movie provides ample critical space to discuss the notion of traumatic memory.

Singular limit problem for the Keller–Segel system and drift-diffusion system in scaling critical Besov–Morrey spaces

A singular limit problem for the Cauchy problem of the Keller–Segel equation is considered in a critical function space based on Morrey spaces. A solution to the Keller–Segel system in a scaling critical function space converges to a solution to the drift-diffusion system of parabolic-elliptic type in the critical space strongly as the relaxation time tends to infinity. The key ingredient is a Banach space-valued Lorentz space in time. By the careful use of the real interpolation, a sharp estimate for the heat semigroup is obtained.

Cultures of antibiotic prescribing in medical intensive care

Antimicrobial resistance (AMR) continues to present a challenge to international healthcare systems and structures of public health. The focus on optimizing antibiotic prescribing in human populations has challenged healthcare systems charged with making responsible their physician-prescribers. In the United States, physicians in almost every specialty and role use antibiotics as part of their therapeutic armamentariums. In United States hospitals, most patients are administered antibiotics during their stay. Therefore, antibiotic prescribing and utilization is a commonly accepted part of medical practice. In this paper, we utilize social science work on antibiotic prescribing to examine a critical space of care in United States hospital settings. From March to August 2018, we used ethnographic methods to study hospital-based medical intensive care unit physicians at the offices and hospital floors they frequent in two urban United States teaching hospitals. We focused on eliciting the interactions and discussions surrounding antibiotic decision-making that are uniquely influenced by the context of medical intensive care units. We argue that antibiotic use in the medical intensive care units under study was shaped by urgency, hierarchy, and uncertainty representative of the medical intensive care unit's role within the larger hospital system. We conclude that by studying the culture of antibiotic prescribing in medical intensive care units, we can see more clearly both the vulnerability of the looming antimicrobial resistance crisis and by contrast the perceived insignificance of stewarding antibiotic use when considered alongside the fragility of life amidst acute medical concerns regularly experienced in the unit.

Nucleation, Growth, Sintering, and Densification of Sulfide in 1215MS Free‐Cutting Steel Billet

Herein, the nucleation, growth, aggregation, sintering, and densification of sulfide in 1215MS free‐cutting steel billet with a total oxygen concentration of 70 ppm are investigated. A portion of oxygen in the steel dissolves in sulfide to form oxysulfide, Mn(S,O), which can be single‐particle spherelike (SPS), double‐particle rodlike (DPR), and multi‐particle rodlike (MPR), and SiO2 can precipitate at the outer edge of the SPS and connection in the DPR and MPR inclusion particles to form Mn(S,O)–SiO2 inclusion, which is formed by the change of liquid inclusion, that undergoes monotectic reaction to form oxides and oxysulfide. The possible phase‐transition process can be expressed as (Mn,Si)x(S,O)y(l) → Mn(S,O)(l → s) + (Mn,Si)xOy(s) → Mn(S,O)(s) + SiO2(s). Oxysulfide inclusions can aggregate under the influence of van der Waals and viscous drag forces. The larger the particle, the greater the critical spacing and aggregation force. MPR oxysulfide can be divided into three parts: droplet, flat surface, and neck, which have decreasing chemical potentials in turn. Sintering and densification occur after the aggregation of particles, where surface diffusion of elements dominates, while grain boundary diffusion and bulk diffusion dominate in the densification of particles. Meanwhile, the formation and evolution of five different morphologies of sulfides in 1215MS free‐cutting steels are discussed.

Effects of involuntary and voluntary attention on critical spacing of visual crowding.

Visual spatial attention can be allocated in two distinct ways: one that is voluntarily directed to behaviorally relevant locations in the world, and one that is involuntarily captured by salient external stimuli. Precueing spatial attention has been shown to improve perceptual performance on a number of visual tasks. However, the effects of spatial attention on visual crowding, defined as the reduction in the ability to identify target objects in clutter, are far less clear. In this study, we used an anticueing paradigm to separately measure the effects of involuntary and voluntary spatial attention on a crowding task. Each trial began with a brief peripheral cue that predicted that the crowded target would appear on the opposite side of the screen 80% of the time and on the same side of the screen 20% of the time. Subjects performed an orientation discrimination task on a target Gabor patch that was flanked by other similar Gabor patches with independent random orientations. For trials with a short stimulus onset asynchrony between cue and target, involuntary capture of attention led to faster response times and smaller critical spacing when the target appeared on the cue side. For trials with a long stimulus onset asynchrony, voluntary allocation of attention led to faster reaction times but no significant effect on critical spacing when the target appeared on the opposite side to the cue. We additionally found that the magnitudes of these cueing effects of involuntary and voluntary attention were not strongly correlated across subjects for either reaction time or critical spacing.

Mechanical synergistic interaction between adjacent corrosion defects and its effect on pipeline failure

This work provides a new comprehensive assessment method to determine the complex mechanical interaction of adjacent corrosion defects. Firstly, a three-dimensional (3D) finite element model of pipelines containing adjacent defects (involving longitudinally aligned, circumferentially aligned, and diagonally aligned defects) was developed and validated by full-scale burst tests. Then, the synergistic stress interaction between adjacent defects was analyzed, and the relationship between the burst position of the pipeline and defect spacing was determined. At last, the applicability of several commonly used critical spacing rules for identifying the interaction between adjacent defects was compared and discussed in detail. The results show that the failure position of the pipeline containing adjacent defects is related to the relative position of defects. For longitudinally aligned corrosion defects, the stronger the interaction between defects (i.e., the shorter the distance between two defects), the closer the failure position of the pipeline to the center of the defect spacing. For circumferentially aligned corrosion defects, the failure position of the pipe tends to move from the defect edge to the geometric center of the defect with increasing defect spacing. For diagonally aligned defects, the failure position is generally located on the path connecting the defect and the spacing. The currently available evaluation criteria for identifying circumferentially interacting defects display the most accuracy, and the identification effect of diagonally aligned defects is the poorest. In addition, the critical spacing rule proposed by Li presents the highest precision in identifying the interacting defects. The results are expected to provide a stress synergistic failure assessment method for pipelines containing cluster corrosion defects in engineering.

Nature on Trial: Probing Cosmic Warfare in Akwanya’s Pilgrim Foot and Leopardi’s “Dialogue between Nature and an Icelander”

In his religious and philosophical persuasion, Amechi Akwanya seeks to reconceptualize the concept of human suffering, an idea that is validated in the representation of cosmic warfare in the first sequence of his poetry collection, Pilgrim Foot: A Collection of Poems. Interestingly, this sequence of Akwanya's poetry shares common philosophical ideation with Leopardi's "Dialogue between Nature and an Icelander" in their interrogation of the history of human experience, an observation not yet captured by critical scholarship. Thus in its attempt to cover up this critical space, this article seeks to juxtapose Akwanya's poetry and Leopardi's dialogue to illuminate how art subjects Nature to cross-examination for her alleged hostility toward man. Working within the framework of the Hegelian concept of cosmic contradiction, of the end having already been determined at "the beginning," and Nietzsche's Heraclitean theory, the paper offers a critical examination of not only Nature's burden of guilt in human plight but also how art serves as an outlet for transcending cosmic warfare.

Evaporation of twin drops: Effect of acoustics and spacing

The study investigates how an acoustic field influences evaporation and internal circulation of twin drops when their in-between horizontal spacing varies. The acoustic source is a simple sine wave (i) with and (ii) without white noise at various frequencies. The circulation and outer flow are visualized. Maximum evaporation rate and circulation are found for the lowest frequency and highest spacing. The rate rises with the spacing for a given frequency up to a critical distance. The evaporation becomes almost identical beyond the critical spacing. A correlation among the spacing, evaporation rate, and outer flow velocity is demonstrated. The rate becomes lowest for a given frequency at the least spacing since the vapors accumulated in the surrounding are not swept out by the acoustic-induced flow. The visualization shows a horizontal outer flow, which becomes vertical with the rise in spacing because the acoustic wave can sweep the vapor out. The horizontal flow for the least spacing transforms itself to vertical when the wave amplitude is raised. The evaporation thus rises because the wave now sweeps the vapors out. We show that the perception that any acoustic wave enhances the evaporation of multiple nearby drops is incorrect. The evaporation and circulation decline faster with the rise in frequency since the surrounding flow becomes weak. Thus, we show how the spacing influences the evaporation when acoustic is incident and how the evaporation can be raised by sweeping the accumulated vapor out using higher amplitude acoustics for the closer drops.

The problem with decolonisation: entanglements in the politics of knowledge

AbstractIn the heat of the decolonisation struggles of the 2000s, there has been little space or tolerance for conceptual criticism of this important moment in global history. Using the South African case, this article outlines some of the dilemmas of decolonisation as a concept and method for dealing with legacy knowledge in the aftermath of colonialism and apartheid. The status of whites as citizens rather than colonials, the lack of determination of meanings of decolonisation within public universities, and the defanging of a potentially radical concept are among the concerns raised in this critical work on the uptake of the idea in post-apartheid society. What this criticism points to is the need for a theory of institutions when dealing with radical curriculum change rather than a politics that relies so much on the rhetorical, the symbolic and the performative in the demand for decolonisation.

Translanguaging as a space of simultaneity: Theorizing translanguaging pedagogies in English medium schools from a spatial perspective

AbstractThis article theorizes translanguaging as a space of simultaneity to analyze how teachers use translanguaging to create a multilingual classroom space and engage students with their multilingual identities and epistemologies in the classroom. The data in this article are drawn from an ethnographic study of language policies and practices in a public school in the hills of eastern Nepal. The analysis of classroom anecdotes, observation notes, and interviews with teachers reveals that translanguaging reconfigures the classroom as a critical social space where students’ identities are recognized as multilingual and multiepistemic beings representing their home, community, and school spaces. I argue that translanguaging pedagogies should pay attention to connecting the perceived, conceived, and lived spaces of students to help them resist unequal pedagogies and reclaim their identities as multilingual and multiepistemic subjects. The findings of the study imply that a spatial perspective on translanguaging helps teachers expand the scope of translanguaging pedagogies to transform a monolingualized institutional space as a space of simultaneity that embraces multilingual language practices, transformative ideologies, and the lived experiences of students.

Music, performance and ZANU-PF’s hegemony in Mugabe’s newly independent Zimbabwe

The premise of this article is that popular music was a critical space for enforcing hegemonic dominance of ZANU-PF during the first decade of its rule, as perhaps in other eras. When it assumed power in 1980, ZANU-PF did not hide its intention to establish single-party rule, which was then popular across Africa. Top among competing priorities for the new regime was removing all centres of political opposition or resistance. But PF-ZAPU, ZANU-PF’s erstwhile liberation war rival, threatened this vision in south-western Zimbabwe, where it enjoyed significant support. We analyse music that promoted ZANU-PF hegemony in the context of the Gukurahundi ‘genocide’ in the early 1980s, a campaign that was part of the desire for complete dominance of Zimbabwe. The music contained a celebratory discourse spreading fear and emotional violence, thus censoring and suffocating competing narratives about the new state.

인류세의 글쓰기

By situating “transpacific” as a critical space that allows oceanic exchange between Japan and Canada, the past and the present, and human and nonhuman, this essay critically examines how Ozeki’s third novel, A Tale for the Time Being (2013), helps us apprehend “slow violence,” one that is hard to see or feel due to the workings of time and distant locations. While mainstream Anthropocene discourse has tended to focus more on the perspectives of white elites, writers and scientists based in the Global North, Ozeki’s novel draws the reader’s attention to the fluidity of oceanic movements and intentionally blurs the boundaries between human history and environmental history, especially the links between nuclear bombing in Japan during the World War II and the Fukushima Daiichi nuclear disaster in 2011, in order to emphasize a complex crisis for both human and nonhuman on a planetary scale. Building on what Elizabeth DeLoughrey terms “the oceanic turn” in literatary studies, I argue that Ozeki’s A Tale for the Time Being challenges and works to decolonize the discourses of the Anthropocene and thus invites us to imagine more just and sustainable environmental futures for the more-than-human world.

Killing a “Monster”: Lisa Montgomery, Carceral Logics, and the Rhetoric of Sexual Trauma

What happens when we treat sexual trauma as a disability? This article examines the federal execution case of Lisa Montgomery, who murdered Bobbie Jo Stinnett and kidnapped her baby, with this question as its motivation. Prior to execution, dozens of clemency petitions circulated publicly, revealing how Montgomery was repeatedly subjected to instances of sexual, physical, and emotional abuse across her lifetime, generating robust commentary about mental disability and sexual violence. I argue that these petitions—even in their effort to retrain public opinion of how Montgomery’s history shaped her actions—upheld carceral logics that insisted Montgomery must pay for her bodymind, reinforcing the idea that mentally ill women do not belong in the public sphere. By carving critical space for sexual violence within feminist disability studies, this article demonstrates how the tensions that ensue when categorizing the aftermath of sexual trauma as a disability result from a discursive incapacity of the state.

Translanguaging Framework for Deaf Education

In this conceptual article, the authors introduce the Translanguaging Framework for Deaf Education (TFDE), drawing upon two perspectives on language and learning: crip linguistics and critical translanguaging space. The TFDE is a retheorization of the Language Zone, a pedagogical framework for supporting language learning in deaf education, and is designed to support educators to approach language use and users from an asset-oriented perspective. In line with this stance, the TFDE validates the linguistic resources deaf students bring to the classroom and encourages students’ full use of their communicative repertoires for meaning making, while also working to expand their linguistic resources and increase communicative flexibility. Examples of translanguaging pedagogical practices with deaf students, such as coming to a shared understanding, building metalinguistic knowledge, and honing communication for external audiences, are explained and illustrated through classroom scenarios with deaf students. Readers are also provided with tools for critically analyzing the social context to ensure accessible and equitable language environments for deaf students and to protect spaces for the use of minoritized languages such as ASL.