College leadership decisions and experiences during the COVID-19 pandemic: an elite interview study.

OBJECTIVE: This study at a US Native American-serving Nontribal Institution (NASNTI) deeply analyzed collegiate leadership's responses and experiences during the first year of the COVID-19 pandemic. PARTICIPANTS: Elite interviews were conducted between April and June 2021 with the college president, provost, dean of student engagement, human resources director, and chief of police. Interviewees were purposively selected due to their positions of authority. METHODS: Each one-hour interview used a semi-structured guide for standardization and was conducted either virtually or in-person while following COVID-19 protocols. The general inductive method was used to identify nodes and categories within the transcripts. RESULTS: Six nodes (conceptual domains) and 18 categories were identified. Though there was variability in interviewee emphasis, the respondents described the motivations, drivers, and sentiment behind their decision-making in a transparent way. CONCLUSIONS: NASNTI leadership reported being able to navigate the pandemic by emphasizing transparency and engaging students, while working alongside the community.

Evolution of storytelling pedagogy in global health course at a U.S. Native American-Serving Nontribal Institution from 2019 to Spring 2023.

Background and purpose: Responding to COVID-19-induced disruptions to traditional teaching methodologies, and considering the relevance of narratives among indigenous populations, "storytelling as pedagogy" was developed and implemented in the undergraduate Global Health course in a Native American-Serving Nontribal Institution (NASNTI) in Colorado. Methods: We describe the evolving pedagogic adjustments and storytelling strategies incorporated into the global health course from Fall 2019 to Spring 2023. This entailed before the COVID-19 in-person format, online digital storytelling during the pandemic emergency, the HyFlex and hybrid classes with the emergence of "new normals," and finally the gradual move to in-person classes. The story arc in the course included the following: (1) Course learning outcomes revisited and the course syllabus language framed based on the native philosophies of empowerment education and experiential learning, (2) students' inputs sought to incorporate socioculturally responsive topics in the course syllabus (e.g., dental health disparities among indigenous populations), (3) strategic and non-threatening shifts such as "no textbooks" and "no finals" introduced, (4) global health thought partners invited by the course instructor and coached to use story-based teaching methods, (5) use of first-person trauma-informed storytelling methods to teach specific global health topics, and (6) students undertook gratitude journaling, a scaffolding exercise of writing letters on global health topics to global health thought partners. Results: Storytelling as pedagogy was most effective in the in-person format, while digital storytelling during the COVID-19-induced online classes was extremely challenging considering the stark digital divide in the Navajo Nation. First-person, trauma-informed storytelling is a helpful approach to discuss insider-outsider perspectives and can potentially establish sustainable trustworthy relationships among the students, instructor, and global health thought leaders. Gratitude journaling and photovoice can be tweaked as powerful storytelling methods to build students' interaction-based critical thinking, intercultural humility, and professional networking. Conclusion: Mapping storytelling pedagogies' best practices can be useful in developing a granulated understanding of this strategy and utilizing them across diverse disciplines in higher education. Faculty capacity building is recommended to enable the former to conceptualize culturally responsive storytelling pedagogies and create assessment plans to assess students' learning outcomes through the utilization of this method.

Students' COVID-19 vaccine behaviors, intentions, and beliefs at a US Native American-Serving Nontribal Institution (NASNTI).

OBJECTIVE: Multiple national and international studies of college student COVID-19 vaccination have been recently published, providing important descriptive information and a conceptual basis to inform future decisions about infectious disease prevention in higher education settings. Yet almost no research has examined Native American-Serving Nontribal Institutions (NASNTIs), which occupy a unique space in US higher education in terms of structure and students served. To address that gap, this report describes results from a two-wave cross-sectional survey administered at a NASNTI in Durango, Colorado, as part of a larger study of COVID-19 campus response. Surveys were administered prior to (wave one) and following (wave two) statewide availability of the COVID-19 vaccine for ages 16+. Comparisons between waves used Cramer's V and Mann-Whitney U tests. RESULTS: A total of 283 students responded to wave one, and 186 responded to wave two. Notable results included a self-reported COVID-19 vaccination rate (40.1%) at wave one that far exceeded parallel national rates. Injunctive and disjunctive normative beliefs were also less supportive of vaccination among the unvaccinated at wave two compared to wave one. Findings from this study should be considered in the context of all available evidence and not used to make inferences in isolation.

Evolution of Tiling-like Crack Patterns in Maturing Columnar Joints.

Fracture or cracking essentially involves the formation of new interfaces. These patterns are usually studied as two-dimensional mosaics. The new surface that opens up is in the third dimension, along the thickness of the sample. The thickness is usually very small compared to the lateral dimensions of the pattern. A spectacular and distinctive departure from these everyday examples of cracks are columnar joints. Here, molten volcanic lava, by the sea, cools and cracks under appropriate thermal and elastic conditions, causing the crack system to grow downward, creating long, vertical columns with polygonal cross-section. The focus of this paper is the study of the elongated interfaces of these columns: how the cross-section of their outlines gradually undergoes a metamorphosis from a disordered-looking Gilbert tessellation to a well-ordered hexagonal Voronoi pattern. As the columns grow downward to lengths of several meters (in natural systems), their outline continuously changes, the center may shift, causing the column to twist. For the first time, the evolution of these crack mosaics has been simulated and mapped as a trajectory of a 4-vector tuple in a geometry-topology domain. The trajectory of the columnar joint systems is found to depend on the crack seed distribution and crack orientation. An empirical relationship between the system energy and the crack mosaic shape parameter λ has been proposed on the basis of principles of fracture mechanics. The total system energy shows a power-law dependence on λ with the exponent ß âˆ¼ 0.3 and λ ≈ 0.75 at crack maturation. The parameter values are validated by matching the proposed relation with energy estimates existing in the literature. The relation not only matches the visible changes in geometry but also provides a feasible measure of the energy of the system. The geometric energy for the polygonal mosaics in the transverse section has also been estimated as a function of time. The geometric energy moves toward a minimum as the mosaic becomes more Voronoi-like at maturation.

Aggregation patterns of copper sulphate salt via droplet drying: mediation by surface hydrophobicity and salt concentration.

Patterns in drying droplets formed from colloidal solution of copper sulphate and gelatin are investigated with respect to variation of substrate hydrophobicity and salt concentration. Hydrophilic substrates as (i) glass, (ii) quartz and hydrophobic substrate as (iii) polypropylene (PP) have been used. It is observed that the dry residue pattern of salt crystals shows curved branches of crystalline aggregate growth about droplet centre for hydrophilic substrates, while thick, light and dark concentric bands of aggregates are observed for hydrophobic substrates. The geometry and topology of the patterns have been characterized through an analysis of fractal dimension and the topological measure, Euler characteristic. The fractal dimension of the deposit increases substantially with salt concentration for hydrophilic substrates, but decreases with concentration for hydrophobic substrate. Our analysis leads us to propose that an optimal viscosity contrast that facilitates prominent viscous fingers is a function of contact angle and salt concentration. We propose that substrate hydrophobicity and salt concentration together are responsible for DLA-like aggregation in evaporating droplets.

Perceived enablers and barriers of community engagement for vaccination in India: Using socioecological analysis.

BACKGROUND: There is high level policy consensus in India that community engagement (CE) improves vaccination uptake and reduces burden of vaccine preventable diseases. However, to date, vaccination studies in the country have not explicitly focused on CE as an outcome in and of itself. Therefore, this study sought to examine the barriers and enablers of community engagement for vaccination in India. METHODS: Employing qualitative methods, twenty-five semi-structured elite interviews among vaccine decisionmakers' were triangulated with twenty-four national-level vaccine policy documents and researcher field notes (December 2017 to February 2018). Data collected for this study included perceptions and examples of enablers of and barriers to CE for vaccination uptake. Concepts, such as the absence of formal procedures or data collection approaches related to CE, were confirmed during document review, and a final convening to review study results was conducted with study respondents in December 2018 and January 2019 to affirm the general set of findings from this study. The Social Ecological Model (SEM) was used to organize and interpret the study findings. RESULTS: Although decisionmakers and policy documents generally supported CE, there were more CE barriers than facilitators in the context of vaccination, which were identified at all social-ecological levels. Interviews with vaccine decisionmakers in India revealed complex systemic and structural factors which affect CE for vaccination and are present across each of the SEM levels, from individual to policy. Policy-level enablers included decisionmakers' political will for CE and policy documents and interviews highlighted social mobilization, whereas barriers were lack of a CE strategy document and a broad understanding of CE by decisionmakers. At the community level, dissemination of Social-behavioral Change Communication (SBCC) materials from the national-level to the states was considered a CE facilitator, while class, and caste-based power relations in the community, lack of family-centric CE strategies, and paternalistic attitude of decisionmakers toward communities (the latter reported by some NGO heads) were considered CE barriers. At the organizational level, partnerships with local organizations were considered CE enablers, while lack of institutionalized support to formalize and incentivize these partnerships highlighted by several decisionmakers, were barriers. At the interpersonal level, SBCC training for healthcare workers, sensitive messaging to communities with low vaccine confidence, and social media messaging were considered CE facilitators. The lack of strategies to manage vaccine related rumors or replicate successful CE interventions during the during the introduction and rollout of new vaccines were perceived as CE barriers by several decisionmakers. CONCLUSION: Data obtained for this study highlighted national-level perceptions of the complexities and challenges of CE across the entire SEM, from individual to systemic levels. Future studies should attempt to associate these enablers and barriers with actual CE outcomes, such as participation or community support in vaccine policy-making, CE implementation for specific vaccines and situations (such as disease outbreaks), or frequency of sub-population-based incidents of community resistance and community facilitation to vaccination uptake. There would likely be value in developing a population-based operational definition of CE, with a step-by-step manual on 'how to do CE.' The data from this study also indicate the importance of including CE indicators in national datasets and developing a compendium documenting CE best-practices. Doing so would allow more rigorous analysis of the evidence-base for CE for vaccination in India and other countries with similar immunization programs.

A qualitative analysis of vaccine decision makers' conceptualization and fostering of 'community engagement' in India.

BACKGROUND: Globally, and in India, research has highlighted the importance of community engagement in achieving national vaccination goals and in promoting health equity. However, community engagement is not well-defined and remains an underutilized approach. There is also paucity of literature on community engagement's effectiveness in achieving vaccination outcomes. To address that gap, this study interviewed Indian vaccination decision makers to derive a shared understanding of the evolving conceptualization of community engagement, and how it has been fostered during India's Decade of Vaccines (2010-2020). METHODS: Semi-structured interviews were conducted with 25 purposefully sampled national-level vaccine decision makers in India, including policymakers, immunization program heads, and vaccine technical committee leads. Participants were identified by their 'elite' status among decisionmakers in the Indian vaccination space. Schutz' Social Phenomenological Theory guided development of an a priori framework derived from the Social Ecological Model. The framework helped organize participants' conceptualizations of communities, community engagement, and related themes. Inter-rater reliability was computed for a subsample of coded interviews, and findings were validated in a one-day member check-in meeting with study participants and teams. RESULTS: The interviews successfully elucidated participants' understanding of key terminology ("community") and approaches to community engagement propagated by the vaccine decision makers. Participants conceptualized 'communities' as vaccine-eligible children, their parents, frontline healthcare workers, and vaccination influencers. Engagement with those communities was understood to mean vaccine outreach, capacity-building of healthcare workers, and information dissemination. However, participants indicated that there were neither explicit policy guidelines defining community engagement nor pertinent evaluation metrics, despite awareness that community engagement is complex and under-researched. Examples of different approaches to community engagement ranged from vaccine imposition to empowered community vaccination decision-making. Finally, participants proposed an operational definition of community engagement and discussed concerns related to implementing it. CONCLUSIONS: Although decision makers had different perceptions about what constitutes a community, and how community engagement should optimally function, the combined group articulated its importance to ensure vaccination equity and reiterated the need for concerted political will to build trust with communities. At the same time, work remains to be done both in terms of research on community engagement as well as development of appropriate implementation and outcome metrics.

Branched crack patterns in layers of Laponite® dried under electric fields: Evidence of power-laws and fractal scalin>.

In the present work we report crack patterns formed in aqueous Laponite® gel in a rectangular box, while exposed to a uniform static electric field. The crack pattern shows a very interesting tree-like geometry extending from the positive to the negative electrode. At the positive electrode a large number of cracks appear at first and merge with each other in stages thus forming tree-like fractal structures. These structures are reminiscent of the Bethe lattice or Cayley tree. The "trees" divide the system into peds of varying size, with numerous smaller ones on the positively charged end, gradually increasing in size, and decreasing in number towards the negative end. If the cumulative distribution of the number of peds exceeding a certain area in size, is plotted against that area, a power-law relation is obtained. This implies a scale-invariant fractal character of the pattern. For a given system size, the exponent of the power-law has a nearly constant value for different applied voltages. We present an experimental study demonstrating this behaviour and discuss how it compares with similar distributions of river-basin areas and viscous fingers in a Hele-Shaw cell.

Pilot study of the influence of self-coding on empathy within an introductory motivational interviewing training.

BACKGROUND: Motivational interviewing (MI) is a framework for addressing behavior change that is often used by healthcare professionals. Expression of empathy during MI is associated with positive client outcomes, while absence of empathy may produce iatrogenic effects. Although training in MI is linked to increased therapeutic empathy in learners, no research has investigated individual training components' contribution to this increase. The objective of this study was to test whether a self-coding MI exercise using smartphones completed at hour 6 of an 8-h MI training was superior in engendering empathy to training as usual (watching an MI expert perform in a video clip for the same duration at the same point in the training). METHODS: This was a pilot study at two sites using randomization and control groups with 1:1 allocation. Allocation was achieved via computerized assignment (site 1, United Kingdom) or facedown playing card distribution (site 2, United States). Participants were 58 students attending a university class at one of two universities, of which an 8-h segment was dedicated to a standardized MI training. Fifty-five students consented to participate and were randomized. The intervention was an MI self-coding exercise using smartphone recording and a standardized scoring sheet. Students were encouraged to reflect on areas of potential improvement based on their self-coding results. The main outcome measure was score on the Helpful Responses Questionnaire, a measure of therapeutic empathy, collected prior to and immediately following the 8-h training. Questionnaire coding was completed by 2 blinded external reviewers and assessed for interrater reliability, and students were assigned averaged empathy scores from 6 to 30. Analyses were conducted via repeated-measures ANOVA using the general linear model. RESULTS: Fifty-five students were randomized, and 2 were subsequently excluded from analysis at site 2 due to incomplete questionnaires. The study itself was feasible, and overall therapeutic empathy increased significantly and substantially among students. However, the intervention was not superior to the control condition in this study. CONCLUSIONS: Replacing a single passive learning exercise with an active learning exercise in an MI training did not result in a substantive boost to therapeutic empathy. However, consistently with prior research, this study identified significant overall increases in empathy following introductory MI training. A much larger study examining the impact of selected exercises and approaches would likely be useful and informative.

Narrowing Desiccating Crack Patterns by an Azeotropic Solvent for the Fabrication of Nanomesh Electrodes.

Desiccation of a colloidal layer produces crack patterns because of stress arising out of solvent evaporation. Associated with it is the rearrangement of particles, while adhesion to the substrate resists such movements. The nature of solvent, which is often overlooked, plays a key role in the process as it dictates evaporation and wetting properties of the colloidal film. Herein, we study the crack formation process by using a mixture of solvents, water, and isopropyl alcohol (IPA). Among the various ratios, a water/IPA mixture (15:85 by volume) close to the azeotropic composition possesses unusual evaporation and wetting properties, leading to narrower cracks with widths down to ∼162 nm, uncommon among the known crackle patterns. The dense and narrow crack patterns have been used as sacrificial templates to obtain metal meshes on transparent substrates for optoelectronic applications.

Social Media Outrage in Response to a School-Based Substance Use Survey: Qualitative Analysis.

BACKGROUND: School-based alcohol, tobacco, and other drug use (ATOD) surveys are a common epidemiological means of understanding youth risk behaviors. They can be used to monitor national trends and provide data, in aggregate, to schools, communities, and states for the purposes of funding allocation, prevention programming, and other supportive infrastructure. However, such surveys sometimes are targeted by public criticism, and even legal action, often in response to a lack of perceived appropriateness. The ubiquity of social media has added the risk of potential online firestorms, or digital outrage events, to the hazards to be considered when administering such a survey. Little research has investigated the influence of online firestorms on public health survey administration, and no research has analyzed the content of such an occurrence. Analyzing this content will facilitate insights as to how practitioners can minimize the risk of generating outrage when conducting such surveys. OBJECTIVE: This study aimed to identify common themes within social media comments comprising an online firestorm that erupted in response to a school-based ATOD survey in order to inform risk-reduction strategies. METHODS: Data were collected by archiving all public comments made in response to a news study about a school-based ATOD survey that was featured on a common social networking platform. Using the general inductive approach and elements of thematic analysis, two researchers followed a multi-step protocol to clean, categorize, and consolidate data, generating codes for all 207 responses. RESULTS: In total, 133 comments were coded as oppositional to the survey and 74 were coded as supportive. Among the former, comments tended to reflect government-related concerns, conspiratorial or irrational thinking, issues of parental autonomy and privacy, fear of child protective services or police, issues with survey mechanisms, and reasoned disagreement. Among the latter, responses showed that posters perceived the ability to prevent abuse and neglect and support holistic health, surmised that opponents were hiding something, expressed reasoned support, or made factual statements about the survey. Consistent with research on moral outrage and digital firestorms, few comments (<10%) contained factual information about the survey; nearly half of the comments, both supportive and oppositional, were coded in categories that presupposed misinformation. CONCLUSIONS: The components of even a small online firestorm targeting a school-based ATOD survey are nuanced and complex. It is likely impossible to be fully insulated against the risk of outrage in response to this type of public health work; however, careful articulation of procedures, anticipating specific concerns, and two-way community-based interaction may reduce risk.

Association Between Individual and Intimate Partner Factors and Cervical Cancer Screening in Kenya.

INTRODUCTION: Cervical cancer is the most prevalent cancer among women in Kenya. Although cervical cancer screening could reduce illness and death, screening rates remain low. Kenyan women's individual characteristics and intimate partner factors may be associated with cervical cancer screening; however, a lack of nationally representative data has precluded study until recently. The objective of our study was to examine individual and intimate partner factors associated with cervical cancer screening in Kenya. METHODS: We conducted secondary data analysis of responses by women who completed the cervical cancer screening and domestic violence questions in the Kenya Demographic and Health Survey, 2014 (N = 3,222). By using multivariable regression analyses, we calculated the association of cervical cancer screening with age, religion, education, wealth, recent exposure to family planning on television, head of household's sex, and experience of intimate partner violence. RESULTS: Rates of cervical cancer screening among women in Kenya increased with age. The wealthiest women and women with post-secondary education had greater odds of reporting being screened for cervical cancer than the poorest women and uneducated women. Christians and women exposed to prevention messaging on television had higher odds of screening than Muslims and women with no exposure. Victims of intimate partner violence had lower odds of being screened than women who had not experienced intimate partner violence. CONCLUSION: Identified barriers to screening in this sample mirror previous findings, though with additional nuances. Model fit data and theoretical review suggest that additional, unmeasured variables may contribute to variability in cervical cancer screening rates. Inclusion of additional variables specific to cervical cancer in future national surveys could strengthen the ability to identify factors associated with screening.

Formation of desiccation crack patterns in electric fields: a review.

Desiccation crack formation is an important and interesting part of the broad area of fracture mechanics. Generation of cracks due to drying depends on ambient conditions, which may include externally applied fields. In this review, we discuss the effect of both direct and alternating electrical fields on desiccation crack formation. After a brief introduction to materials which crack on drying, e.g. colloids, clay and ceramics we discuss how they respond to an electric field. Following that, we present an account of experiments and modelling studies performed on granular pastes or clays drying while exposed to an electric field. Specific patterns formed under different geometries, strengths and frequencies of the electric field are described and explained. The review includes work on cracks formed in clay droplets, where a memory effect has been observed and analysed using a generalized calculus formalism.This article is part of the theme issue 'Statistical physics of fracture and earthquakes'.

Crack Patterns in Drying Laponite-NaCl Suspension: Role of the Substrate and a Static Electric Field.

We report the formation of crack patterns in drying films of Laponite-NaCl solution. Crack patterns that develop upon drying aqueous Laponite-NaCl solution change drastically as the amount of NaCl is varied in the solution. In this work, we have investigated the effect of NaCl on drying films of aqueous solution of Laponite under two conditions: (i) when the film is bounded by a wall, as in Petri dish experiments and (ii) when the film does not have any boundary, as in experiments with droplets. In order to obtain insights into the effect of the substrate, the experiments have been done with two different substrates of different hydrophobicities, polypropylene and glass. The formation of crack patterns has been explained on the basis of the wetting and spreading properties of the solution on these substrates and the effect of salt on colloidal aggregation. In this work, we have shown that the presence of salt in aqueous Laponite solution can induce crack patterns depending on the nature of the substrate. Another important aspect of this work is the role of NaCl in crack inhibition in desiccating films of aqueous Laponite, in the presence of static electric field. This effect can be utilized to suppress undesirable crack formation in many applications.

Memory of Electric Field in Laponite and How It Affects Crack Formation: Modeling through Generalized Calculus.

Desiccation crack formation is affected by the presence of electric fields. We show here that the field effect not only is at work while the power supply is on but also leaves a memory even after switching off. The time required for the first appearance of cracks is shown to depend on the voltage of the field as well as the time duration of exposure. We model the system as a leaky capacitor described by a fractional order derivative in the constitutive equation. This gives a good fit to experimental data and explains the memory effect.

Fitting HIV Prevalence 1981 Onwards for Three Indian States Using the Goals Model and the Estimation and Projection Package.

Models are designed to provide evidence for strategic program planning by examining the impact of different interventions on projected HIV incidence. We employed the Goals Model to fit the HIV epidemic curves in Andhra Pradesh, Maharashtra and Tamil Nadu states of India where HIV epidemic is considered to have matured and in a declining phase. Input data in the Goals Model consisted of demographic, epidemiological, transmission-related and risk group wise behavioral parameters. The HIV prevalence curves generated in the Goals Model for each risk group in the three states were compared with the epidemic curves generated by the Estimation and Projection Package (EPP) that the national program is routinely using. In all the three states, the HIV prevalence trends for high-risk populations simulated by the Goals Model matched well with those derived using state-level HIV surveillance data in the EPP. However, trends for the low- and medium-risk populations differed between the two models. This highlights the need to generate more representative and robust data in these sub-populations and consider some structural changes in the modeling equation and parameters in the Goals Model to effectively use it to assess the impact of future strategies of HIV control in various sub-populations in India at the sub-national level.

Growth kinetics of NaCl crystals in a drying drop of gelatin: transition from faceted to dendritic growth.

We report a study on the kinetics of drying of a droplet of aqueous gelatin containing sodium chloride. The process of drying recorded as a video clearly shows different regimes of growth leading to a variety of crystalline patterns. Large faceted crystals of ∼mm size form in the early stages of evaporation, followed by highly branched multi-fractal patterns with micron sized features. We simulate the growth using a simple algorithm incorporating aggregation and evaporation, which reproduces the cross-over between the two growth regimes. As evaporation proceeds, voids form in the gel film. The time development of the fluid-void system can be characterized by the Euler number. A minimum in the Euler number marks the transition between the two regimes of growth.

Topology of desiccation crack patterns in clay and invariance of crack interface area with thickness.

We study the crack patterns developed on desiccating films of suspensions of three different clays-bentonite, halloysite nanoclay and laponite on a glass substrate. Varying the thickness of the layer, h gives the following new and interesting results: i) We can identify a critical thickness h c for bentonite and halloysite, above which isolated cracks join each other to form a fully connected network. ii) A topological analysis involving the Euler number is shown to be useful for characterising the patterns. iii) We find, further, that the total vertical surface area of the clay A v, which has opened up due to cracking, and the total area of the glass substrate A s, exposed by the hierarchical sequence of cracks are constant, independent of the layer thickness for a certain range of h. These results are shown to be consistent with a simple energy conservation argument, neglecting dissipative losses. Finally we show that if the crack pattern is viewed at successively finer resolution, the total cumulative area of cracks visible at a certain resolution scales with the layer thickness.

Crack formation under an electric field in droplets of laponite gel: memory effect and scaling relations.

When a colloidal gel dries through evaporation, cracks are usually formed, which often reveal underlying processes at work during desiccation. Desiccating colloid droplets of a few hundred microliters size show interesting effects of pattern formation and cracking which makes this an active subject of current research. Because aqueous gels of clay are known to be strongly affected by an electric field, one may expect crack patterns to exhibit a field effect. In the present study we allow droplets of laponite gel to dry under a radial electric field. This gives rise to highly reproducible patterns of cracks, which depend on the strength, direction, and time of exposure to the electric field. For a continuously applied DC voltage, cracks always appear on dissipation of a certain constant amount of energy. If the field is switched off before cracks appear, the observed results are shown to obey a number of empirical scaling relations, which enable us to predict the time of appearance and the number of cracks under specified conditions. Scanning electron microscopy (SEM) images of the surface between the macroscopic cracks show the presence of microcracks, which are wider and more numerous when no electric field is applied. The microcracks are reduced in the presence of stronger fields.

Electric-field-induced crack patterns: experiments and simulation.

We report a study of crack patterns formed in laponite gel drying in an electric field. The sample dries in a circular petri dish and the field is radial, acting inward or outward. A system of radial cracks forms in the setup with the center terminal positive, while predominantly cross-radial cracks form when the center is at a negative potential. The laponite accumulates near the negative terminal making the layer thicker at this end. A spring model on a square lattice is used to simulate the desiccation crack formation, with an additional radial force acting due to the electric field. With the radial force acting outward, radial cracks form and for the reversed field cross-radial cracks form. This conforms to the observation that laponite platelets become effectively positive due to overcharging and are attracted towards the negative terminal.