Direct Field Research Articles

Direct Magnetic Field Imaging by Advanced Differential Phase Contrast Scanning Transmission Electron Microscopy

Direct Magnetic Field Imaging by Advanced Differential Phase Contrast Scanning Transmission Electron Microscopy

Evaluating Commercial Electrical Neuromodulation Devices with Low-Cost Neural Phantoms

Non-invasive transcranial electrical stimulation is a category of neuromodulation techniques used for various disorders. Although medically approved devices exist, the variety of consumer electrical stimulation devices is increasing. Because clinical trials and animal tests are costly and risky, using a brain phantom can provide preliminary experimental validation. However, existing brain phantoms are often costly or require excessive preparation time, precluding their use for rapid, real-time optimization of stimulation settings. A limitation of direct electric fields in a phantom is the lack of 3D spatial resolution. Using well-researched modalities such as transcranial direct current stimulation (tDCS) and newer modalities such as amplitude-modulated transcranial pulsed-current stimulation (am-tPCS), a range of materials was tested for use as electrical phantoms. Based on cost, preparation time, and efficiency, ground beef and agar gel with a 10% salt mix were selected. The measured values for the total dosages were 0.55 W-s for am-tPCS and 0.91 W-s for tDCS. Due to a low gain on the recording electrodes, the signal efficiency measured against the power delivered was 4.2% for tDCS and 3.1% for am-tPCS. Issues included electrodes shifting in the soft material and the low sensitivity of the recording electrodes. Despite these issues, the effective combination of the phantom and recording methodologies can enable low costs and the rapid testing, experimentation, and verification of consumer neuromodulation devices in three dimensions. Additionally, the efficiency factors (EFs) between the observed dosage and the delivered dosage could streamline the comparison of experimental configurations. As demonstrated by comparing two types of electrical neuromodulation devices across the 3D space of a phantom, EFs can be used in conjunction with a cost-effective, time-expedient phantom to rapidly iterate and optimize stimulation parameters.

Lifting Directional Fields to Minimal Sections

Directional fields, including unit vector, line, and cross fields, are essential tools in the geometry processing toolkit. The topology of directional fields is characterized by their singularities. While singularities play an important role in downstream applications such as meshing, existing methods for computing directional fields either require them to be specified in advance, ignore them altogether, or treat them as zeros of a relaxed field. While fields are ill-defined at their singularities, the graphs of directional fields with singularities are well-defined surfaces in a circle bundle. By lifting optimization of fields to optimization over their graphs, we can exploit a natural convex relaxation to a minimal section problem over the space of currents in the bundle. This relaxation treats singularities as first-class citizens, expressing the relationship between fields and singularities as an explicit boundary condition. As curvature frustrates finite element discretization of the bundle, we devise a hybrid spectral method for representing and optimizing minimal sections. Our method supports field optimization on both flat and curved domains and enables more precise control over singularity placement.

Fabric Tessellation: Realizing Freeform Surfaces by Smocking

We present a novel method for realizing freeform surfaces with pieces of flat fabric, where curvature is created by stitching together points on the fabric using a technique known as smocking. Smocking is renowned for producing intricate geometric textures with voluminous pleats. However, it has been mostly used to realize flat shapes or manually designed, limited classes of curved surfaces. Our method combines the computation of directional fields with continuous optimization of a Tangram graph in the plane, which together allow us to realize surfaces of arbitrary topology and curvature with smocking patterns of diverse symmetries. Given a target surface and the desired smocking pattern, our method outputs a corresponding 2D smocking pattern that can be fabricated by sewing specified points together. The resulting textile fabrication approximates the target shape and exhibits visually pleasing pleats. We validate our method through physical fabrication of various smocked examples.

Communication Model in Managing Geothermal Power Plant Conflicts on Serang Regency, Indonesia

Aims: The construction of Geothermal Power Plants in several regions in Indonesia is currently always characterized by conflict and opposition from local communities, including in Serang Regency. One of the main issues is the company’s inappropriate communication strategy, resulting in a lack of community acceptance and leading to conflicts. The research focuses on the different stages of conflict, behavior and communication of conflicting parties within managing conflict strategies. Researchers utilize Galtung's conflict model and the convergence-divergence communication theory. Methodology: The research method used is qualitative research through the examination of case studies. This was done because the problems in this research remained unclear, holistic, complex, dynamic and full of meaning. Meanwhile, the data collection techniques used in this research were documentation obtained 73 news published by 35 online media covering statistics on yearly citizen actions and newspaper publications, news topics or discussions, and online news coverage on the construction of the Geothermal Power Plant in Serang regency, Indonesia. Also, with direct field observations and in-depth interviews with several informants at the study location. Results: Based on research findings, the Geothermal Power Plant conflict went through 4 stages, including the initial conflict phase; conflict phase; the trust-building phase leading to conflict resolution; and the conflict resolution phase. Meanwhile, based on Galtung's theory, conflict occurs when there is a discrepancy between the socialization provided by the company and the community’s direct experiences, leading to rejection through various actions. The divergent communication approach utilized by the company towards the affected communities resulted in different interpretations, ultimately causing the root of the conflict. Conclusion: The conflict stages in the Geothermal Power Plant development project in Serang regency are divided into several phases that closely related with communication occurred between company, government and the local communities. Lack of communication formed negative opinions about the project developers, leading them to oppose the construction of the Geothermal project. The convergent communication model combined with other communication models such as open, participatory and supportive communication is considered to be highly effective in addressing conflicts.

Data-driven image mechanics (D2IM): A deep learning approach to predict displacement and strain fields from undeformed X-ray tomography images – Evaluation of bone mechanics

The recent advent of deep learning (DL) has enabled data-driven models to pave the way for the full exploitation of rich image datasets from which physics can be learnt. Here we propose a novel data-driven image mechanics (D2IM) approach that learns from digital volume correlation (DVC) displacement fields of vertebrae, predicting displacement and strain fields from undeformed X-ray computed tomography (XCT) images. D2IM successfully predicted the displacements in all directions, particularly in the cranio-caudal direction of the vertebra, where high correlation (R2=0.94) and generally minimal errors were obtained compared to the measured displacements. The predicted axial strain field in the cranio-caudal direction of the vertebra was also consistent in distribution with the measured one, displaying generally reduced errors in the regions within the vertebral body. The application of D2IM to lower resolution imaging in initial testing provides promising results indicating the future viability of integrating this technology into a clinical setting. This is the first study using experimental full-field measurements on bone structures from DVC to inform DL-based models such as D2IM, which represents a major contribution in the prediction of displacement and strain fields based only on the greyscale content of undeformed XCT images. In future, D2IM will incorporate a range of biological structures and loading scenarios for accurate prediction of physical fields, aiming at clinical translation for improved diagnostics. Data AvailabilityCode for preparing dataset, training D2IM model and visualising/analysing results has been hosted on GitHub: https://github.com/PeterSoar/D2IM_PrototypeThe dataset used for this study can be found on Figshare: https://doi.org/10.6084/m9.figshare.25404220.v1

Advanced acoustic simulation of aircraft test environments: integration of the direct field acoustic testing methodology

In aeroacoustic engineering, replicating real-world environments in a controlled setting presents significant opportunities for reduced flight testing but also comes with challenges when precisely simulating the flight environment. This paper introduces an innovative acoustic simulation model that leverages the Boundary Element Method (BEM) and a Direct Field Acoustic Testing (DFAT) simulation module. The primary objective is to virtually reproduce test sound fields that closely mimic the full fluctuating pressure environments aircraft encounter during flight using only loudspeaker arrays. This approach involves virtually reproducing a sophisticated test setup, typically comprising hundreds of drivers actively managed to generate a specific sound field. This setup is designed to virtually replicate various complex pressure environments, such as those produced by a Turbulent Boundary Layer, the complex pressure fields generated by aircraft propellers or jet engines. The use of active noise generation simulation helps determine the feasibility of a given pressure field and the capability of a test facility to simulate it accurately. The virtually reproduced sound fields simulated by this model show remarkable potential in approximating real-world pressure loadings. This capability is particularly useful in establishing pre-test predictions for fuselage testing such as sidewall build-ups: including insulation, and damping treatments, TVAs and TMDs.

Estimating the soil water retention curve by the HYPROP-WP4C system, HYPROP-based PCNN-PTF and inverse modeling using HYDRUS-1D

Due to the difficulty of direct field measurement, soil hydraulic properties are often obtained in laboratory settings using small undisturbed soil samples or estimated indirectly through pedotransfer functions (PTFs). The pseudo-continuous pedotransfer function (PCNN-PTF) is a neural network-based approach for estimating soil hydraulic properties. The main objective of this study was to use field soil moisture and tension data to assess soil water retention curves obtained from the HYPROP-WP4C system and the HYPROP-based PCNN-PTF. The in-situ soil water retention data were simultaneously acquired using Acclima TDT and MeterGroup MPS-6 sensors (every 30 min, May to September 2020) from 11 hybrid bermudagrass plots under different irrigation treatments in Riverside, California. We utilized extended evaporation and dewpoint methods using HYPROP-WP4C (Meter Group Inc., USA) devices to obtain lab-measured SWRCs. In addition, SWRCs were estimated from Rosetta (Schaap et al., 2001) and by inverse modeling in HYDRUS-1D utilizing in-situ moisture retention data. Although the hysteresis impacted field data, overall, there was a good agreement between the in-situ and lab water retention data for most samples, especially within the pF range of 2–3.5. The PCNN-PTF outperformed Rosetta in estimating laboratory (RMSE=0.034 cm3 cm−3 vs 0.063 cm3 cm−3) and in-situ soil moisture data (RMSE=0.048 cm3 cm−3 vs 0.082 cm3 cm−3). Inverse modeling of in-situ data also performed well in estimating the SWRC (RMSE=0.043 cm3 cm−3); however, further attention is required in dry and saturated soil conditions. We developed a simple, free, and easy-to-access tool called PC-PTF for estimating the SWRC using the PCNN-PTF model evaluated in this study. The PC-PTF can be accessed from the Verdi Water Management Group website: http://www.ucrwater.com/software-and-tools.html.

Agriculture Practices in the Danuwar Community of Nuwakot District, Nepal

The Danuwar community is an indigenous group predominantly inhabiting the Terai, and Hilly regions of Nepal, practicing traditional agriculture. This study examines the current agricultural practices of the Danuwar community of Ganesthan, Nuwakot district, Nepal. Primary data were collected from direct field surveys with the help of structured and semistructured questionnaires. Similarly, the necessary secondary data were collected from published and unpublished literatures, and documents of Bidur municipality, Nuwakot. Still, Danuwars are practicing the traditional pattern of agriculture and needs training and skilled-oriented education for their improvement. Given their reliance primarily on agriculture, the transition towards modernization and commercial production of agriculture is pivotal for their socio-economic sustainability. Thus, it is suggested to empower them through technical education, market accessibility, irrigation, transportation, and microfinance activities that shall integrate the Danuwar community into mainstream development and attain self-sustainability.

Mesozoic tectonic evolution and dynamic mechanisms of the northern Bozhong depression of the Bohai Bay Basin, eastern China

The northern Bozhong depression of the Bohai Bay Basin in eastern China is an important area for oil and gas exploration in buried hills, which has complex structural styles and evolutionary processes. Based on 3D seismic and drilling data, the features of the Mesozoic structural deformation of the northern Bozhong depression are analyzed, and the tectonic evolution and dynamic mechanisms are also discussed. The complex Mesozoic structural styles of the northern Bozhong depression are composed of compression, strike-slip, and extension structures, which mainly trend in the near E-W, NW, NE, and NNE directions. Triggered by the collision and subduction between the North China, South China and Izanagi plates and associated stress fields of different periods, natures and directions, the northern Bozhong depression has experienced five stages of deformation at the end of the Middle Triassic, the Late Triassic, the Early-Middle Jurassic, the Late Jurassic-Early Cretaceous and the Late Cretaceous. Cyclical tectonic evolution has controlled the development of structural styles of different strikes and natures and the spatial distribution of strata in the northern Bozhong depression, providing an important foundation for hydrocarbon accumulation in buried hills.

Functional ultrasound neuroimaging reveals mesoscopic organization of saccades in the lateral intraparietal area of posterior parietal cortex.

The lateral intraparietal cortex (LIP) located within the posterior parietal cortex (PPC) is an important area for the transformation of spatial information into accurate saccadic eye movements. Despite extensive research, we do not fully understand the functional anatomy of intended movement directions within LIP. This is in part due to technical challenges. Electrophysiology recordings can only record from small regions of the PPC, while fMRI and other whole-brain techniques lack sufficient spatiotemporal resolution. Here, we use functional ultrasound imaging (fUSI), an emerging technique with high sensitivity, large spatial coverage, and good spatial resolution, to determine how movement direction is encoded across PPC. We used fUSI to record local changes in cerebral blood volume in PPC as two monkeys performed memory-guided saccades to targets throughout their visual field. We then analyzed the distribution of preferred directional response fields within each coronal plane of PPC. Many subregions within LIP demonstrated strong directional tuning that was consistent across several months to years. These mesoscopic maps revealed a highly heterogenous organization within LIP with many small patches of neighboring cortex encoding different directions. LIP had a rough topography where anterior LIP represented more contralateral upward movements and posterior LIP represented more contralateral downward movements. These results address two fundamental gaps in our understanding of LIP's functional organization: the neighborhood organization of patches and the broader organization across LIP. These findings were achieved by tracking the same LIP populations across many months to years and developing mesoscopic maps of direction specificity previously unattainable with fMRI or electrophysiology methods.

Ethnozoological study of Tamang people in Konjyosom Rural Municipality, Lalitpur, Nepal

Ethnic/indigenous people of Nepal have a long history of using animals as medicine. The current study was conducted to determine the ethnozoological relationship, concerning the use of animals, their body parts, and animal products as traditional medicine by the people of Tamang community living in Konjyosom Rural Municipality in Lalitpur district of Nepal. The study was conducted in Chaughare (Ward Number 1), and the ethnozoological data were collected from local people and key informants through interviews, semi-structured questionnaire surveys, and direct field observation. Results showed that 78% of the respondents out of 100 were familiar with using animals as medicines. These people were reported to use 33 different animals (domestic: 8 species and wild: 25 species) for treating various illnesses and diseases in other ways. Considering the age and gender, female respondents and people of age (50-59 years) mainly used to prefer animal consumption for healing their illnesses and diseases. Furthermore, the oral route of administration (81%) and consumption of flesh via cooking were highly preferred. Their tendency to use animals as medicine was higher, so the risk of threatening a few important faunae may exist in the study area. This study will be baseline information for strategic conservation and management of wildlife in the study area or elsewhere within the country.

Direct and inverse magnetocaloric effects in magnetostrictive GdMn2Ge2 with field-induced metamagnetic transition

Heavy rare-earth-based ternary intermetallic compounds with the formula RT2X2 have drawn great interest because of their multiple magnetic transitions and various magnetic structures. Here, anisotropic magnetic behaviors, magnetocaloric effects (MCEs), and magnetostriction effects in single-crystalline GdMn2Ge2 are studied in two different directions. Experiments show a magnetic transition characterized by a sudden decrease in magnetization for μ0H//a and a sharp increase for μ0H//c at Tt. The transition is driven by lower temperatures for μ0H//a, contrasting that for μ0H//c with an increase in the magnetic field. An inverse MCE is observed for μ0H//a with a maximum magnetic entropy change (−ΔSMmax) of −7.4 J kg−1 K−1 (μ0ΔH = 6 T), while a direct MCE is obtained for μ0H//c with an −ΔSMmax of 8.0 J kg−1 K−1 under the same magnetic field change. Moreover, a remarkable field-induced metamagnetic transition and a magnetostriction effect are observed simultaneously at Tt, indicating strong magneto-lattice coupling. The T-μ0H phase diagrams are constructed based on the magnetic properties. The coexistence of direct and inverse MCEs is discussed and is due to the spin-flop of Mn and anisotropic magnetic properties under magnetic fields in different directions.

Goos–Hänchen shifts on spin representation

We analyze the Goos–Hänchen (GH) shift and longitudinal spin splitting (LSS) at a planar interface between two optical media in the spin representation. While these optical effects have been studied previously, we examine the direct and cross-reflected light fields, and their interference from the spin representation to reveal the physical mechanism of the GH shift and establish a quantitative relationship between it and LSS. Furthermore, we show that angular asymmetric spin splitting occurs under the spin representation when linearly polarized light with a phase difference of 180° and an amplitude ratio angle deviating from 45° impinges on the air–glass interface at Brewster’s angle. Finally, we reveal that the spin component field of the reflected light field for the total reflection case is different from that of the Brewster angle reflection, the most typical manifestation is that the intensity of the two spin component fields is not equal.

Study on electrostatic separation technology and characterization of shrimp shell protein

Shrimp shell protein is a high-quality protein with wide-ranging applications in feed, pharmaceuticals, and food industries. However, current methods for its production often involve the use of harsh chemicals, resulting in the generation of polluting effluents, making green alternatives highly desirable. This study combined demineralization of shrimp shell (Fenneropenaeus chinensis, Osbeck, 1765) with ultrafine grinding and electrostatic separation techniques to extract and separate the protein. The research findings revealed that shrimp shell contain 40.64 ± 0.52 % protein, which increased to 52.61 ± 1.12 % after demineralization treatment. Impact grinding, compared with cutting grinding, facilitated the production of demineralized shrimp shell ultrafine powder with more uniform distribution and smaller particle size. However, only demineralized shrimp shell powder obtained through cutting grinding achieved an increase in protein purity from 61.82 ± 0.75 % to 72.72 ± 0.83 % after electrostatic separation. The electrical properties of shrimp shell protein and chitin suggest that shrimp shell protein is more conductive than chitin, while shrimp shell chitin is more insulating and less prone to charge exchange with the counter material in a direct current electric field. The total amino acid content of shrimp shell protein obtained through electrostatic separation (715.831 mg/g protein) was higher than that obtained through traditional wet extraction (533.455 mg/g protein). Additionally, the amino acid score (AAS) of shrimp shell protein obtained via electrostatic separation was higher compared to that obtained via wet extraction. The wet extraction process significantly influenced the nutritional and structural properties of shrimp shell protein. This study confirms the potential application of electrostatic separation technology in the extraction of animal-derived shrimp shell protein.

Direct Field Curve Fitting Method to Determine Hardening Soil Parameter for Geotechnical Projects

Abstract In a wide archipelago country like Indonesia, transporting soil samples for laboratory tests are quite a bit of challenge in terms of cost and time as those need to be transported for weeks to nearest big cities. In-situ tests and correlation methods can be used as an alternative solution for preliminary or detailed design beside having on site laboratory. Correlating in-situ test results to hardening soil parameter (e.g. E 50) is common but it is not clear how those should be adjusted for Plaxis input. Two deep excavation projects and a lateral pile load test are used to see the performance of direct field curve fitting method utilizing SPT correlation to HS parameter. From the analysis, using E 50=4000N for clay soils and E 50=2800N for sand soils as upper bound parameters produce the best results with lesser discrepancy with the field measurements compared to calculations with lower bound parameters. For the deep excavation cases (Case 1 and Case 2), calculated lateral displacement results using upper bound parameters overestimates inclinometers measurement for less than 1.5 cm for both cases. For the case of lateral pile load test (Case 3), calculation using upper bound parameters succeed to capture a high detail of unloading-reloading curves similar to the actual measurement. This method can be used as a technique to design geotechnical projects and it proposes a framework for future research regarding a new possibility to establish various E 50 correlations.

Towards Optimum Service Delivery: A Geospatial Distribution of Financial Institutions in Port Harcourt Urban of Rivers State Nigeria

Financial Institutions in Nigeria are established for the purpose of rendering public and social services to the public. The cashless financial policy briefly introduced by the Federal Government of Nigeria through the Central Bank exposed some flaws of Financial Institutions from discharging her responsibilities with hundreds of customers left displeased and frustrated. The demand for effective and stress free banking services by populace prompted the need for this study which is aimed to examine the geospatial distribution of Financial Institutions in the study area. The study utilizes geospatial technique which involves direct field observation with Germin 76sc GNSS receiver to obtain spatial information of Financial Institution locations in the study area. The observed data were charted in Open Street Map (OSM) of 2022 and were identified as point feature. Arc-GIS 10.1 vector based GIS software was used for processing and map production. The results revealed that commercial banks were not spread across the study area. A total number of One Hundred and Twenty Three (123) Financial Institutions were identified, this cuts across densely urbanized areas, such as Rumuokoro, Diobu, Government Reserved Area, Rumuokwuta and Town axis with very few located in Trans-Amadi axis amongst others. Clustered, linear and random distribution of Financial Institutions were also noted as no Bank was found in highly urbanized areas such as Rukpoku, Ozuoba, Ogbogoro, Rumuagholu and Rumuekini. Establishment of sufficient Financial Institutions at selected locations is essential to ensure optimum services delivery in the study area, factors responsible for the deficiency of Financial Institutions in noted locations should also be addressed.

The development of a sustainable climate resilience building framework for Southern Zimbabwe

Resilience building has increasingly been embraced as a framework for managing climate change and variability induced disaster. The study sought to develop a Sustainable Climate Resilience Building framework for managing climate change adversities in Mwenezi District of Southern Zimbabwe. A mixed method approach which utilized both qualitative and quantitative techniques was used. The choice of two approaches was based on a phenomenological constructivist belief that problems are best solved using multiple sources. The qualitative approach depended on questionnaires, interviews, focus group discussions and direct field observations. The quantitative approach depended on closed ended questions and use of statistical package for social scientists (SPSS version 25.0) for data analysis. Qualitative data was subjected to content analysis. The findings obtained revealed that Non-Governmental Organizations and Government Departments have collaborated and initiated resilience interventions to manage climate change impacts. Some of the interventions implemented can be categorized as crop production and livestock production interventions. However there are some challenges obtained hindering communities’ capacity to build resilience these are namely, ignorance, lack of technical know-how and lack of financial resources to buy resilient inputs on the side of communities. Based on the findings, a Sustainable Climate Resilience Building framework was developed to manage climate change adversities. The researchers recommend communities to adopt a Sustainable Climate Resilience Building framework. This is because the framework provides a pathway for building community resilience to effectively manage climate change adversities.

Assessing the Utility of Uncrewed Aerial System Photogrammetrically Derived Point Clouds for Land Cover Classification in the Alaska North Slope

Uncrewed aerial systems (UASs) have been used to collect “pseudo field plot” data in the form of large-scale stereo imagery to supplement and bolster direct field observations to monitor areas in Alaska. These data supplement field data that is difficult to collect in such a vast landscape with a relatively short field season. Dense photogrammetrically derived point clouds are created and are facilitated to extract land cover data using a support vector machine (SVM) classifier in this study. We test our approach using point clouds derived from 1-cm stereo imagery of plots in the Alaska North Slope region and compare the results to field observations. The results show that the overall accuracy of six land cover classes (bare soil, shrub, grass, forb/herb, rock, and litter) is 96.8% from classified patches. Shrub had the highest accuracy (>99%) and forb/herb achieved the lowest (<48%). This study reveals that the approach could be used as reference data to check field observations in remote areas.

Biomagnetostratigraphy of the Eastern Gobustan’s paleogene rocks

On the territory of Azerbaijan, Paleogene deposits are widespread and often have facies alteration. To address the issues of stratigraphic, paleogeography, facies and paleoecological directions, a detailed stratigraphic basis of both the region as a whole and its individual sections is required. This article presents the results of joint magnetobiostratigraphic studies of the Paleogene deposits of the Greater Caucasus (Azerbaijan) in order to clarify the boundaries of the Paleocene, Eocene, Oligocene and Miocene. Biostratigraphically dated Paleogene deposits of the Khilmili, Pirakushkul, Dzhangi sections (southern slope of the Greater Caucasus) were chosen as the object of study. Paleomagnetic studies of the Paleogene deposits of Azerbaijan showed frequent reversals of the geomagnetic field of this period. The results of scientific studies of the southern slope of the Greater Caucasus confirmed this fact. We have identified two paleomagnetic zones: 1) Khorem (Maastrichtian 70 Ma - Eocene 45 Ma) (zones of reverse polarity prevail in it, but the upper part of the Paleocene has a direct polarity) and 2) Sogdiana (RN-Oligocene and Miocene - characterized by alternating direct and reverse polarity paleomagnetic field). In the Lower Paleocene, 2 subzones of direct polarity were distinguished: Danian and Selandian. The position of the R-zone made it possible to draw the boundary between the Danian and Selandian stages. The identification of a paleomagnetic zone of reverse polarity contributed to the determination of the boundary between the Selandian and Thanetian stages. This result was confirmed by identifying changes in the micro-faunistic composition of deposits and observing the nature of variations in micro-floristic complexes. Such a paleomagnetic zone of reverse polarity is the benchmark (plug) for establishing the boundary between the Mons and Thanetian stages. Keywords: paleomagnetism; southern slope of the Greater Caucasus; Paleogene; magnetostratigraphic boundaries.