Small Cubes Research Articles

Effect of non-additive mixing on entropic bonding strength and phase behavior of binary nanocrystal superlattices.

Non-additive mixing plays a key role in the properties of molecular fluids and solids. In this work, the potential for athermal order-disorder phase transitions is explored in non-additive binary colloidal nanoparticles that form substitutionally ordered compounds, namely, for equimolar mixtures of octahedra + spheres, which form a CsCl lattice compound, and cubes + spheres, which form a NaCl crystal. Monte Carlo simulations that target phase coexistence conditions were used to examine the effect on compound formation of varying degrees of negative non-additivity created by component size asymmetry and by size-tunable indentations in the polyhedra's facets, intended to allow the nestling of neighboring spheres. Our results indicate that the stabilization of the compound crystal requires a relatively large degree of negative non-additivity, which depends on particle geometry and the packing of the relevant phases. It is found that negative non-additivity can be achieved in mixtures of large spheres and small cubes having no indentations and lead to the athermal crystallization of the NaCl lattice. For similarly sized components, athermal congruent transitions are attainable and non-additivity can be generated through indentations, especially for the cubes + spheres system. Increasing indentation leads to lower phase coexistence free energy and pressure in the cubes + spheres system but has the opposite effect in the octahedra + spheres system. These results indicate a stronger stabilizing effect on the athermal compound phase by the cubes' indentations, where a deeper nestling of the spheres leads to a denser compound phase and a larger reduction in the associated pressure-volume free-energy term.

Impact of Visual Cues on Consumers' Freshness Perception of Prepared Vegetables.

Freshness is an important quality attribute for vegetables. Identifying the sensory drivers for freshness is important to promote vegetable consumption. Due to the lack of research on freshness of prepared vegetables, this study focused on the role of visual cues of common vegetables (carrot, beetroot, bell pepper) on perception of freshness. Twenty-seven vegetables were prepared by varying five factors and photographed in a plate: (1) shape (stick, large cube, small cube), (2) vegetable presence for each of the three vegetables (yes, no), (3) number of vegetables conjointly present in the plate (1, 2, 3), (4) color (green bell pepper, yellow bell pepper), (5) combined vegetables prepared with same or different shapes. Freshness was rated online by 156 consumers. Visual cues leading to the main increase in freshness were the stick shape vs. large and small cubes, the absence of beetroot, and the presence of green bell pepper vs. yellow bell pepper. Overall, it seems that visual cues associated with minimally processed vegetables, such as stick shapes, which allow to recognize the vegetables in comparison to cube shapes, promote freshness. These results are particularly valuable for culinary and catering professionals and food industries involved in the preparation and/or manufacturing of prepared vegetables.

Origami-inspired robot folds into more than 1000 shapes

Composed of small cubes, the robot needs only a few motors to be active at any one time to transform between configurations.

Drug-free in vitro activation and autologous transplantation in infertile women with diminished ovarian reserve: An experimental pilot study.

Poor ovarian response and diminished ovarian reserves (DOR) significantly contribute to female infertility. Previous attempts have been made to enhance follicular growth and improve pregnancy outcomes in these participants. This study aimed to assess the efficacy of the in vitro drug-free activation technique of the ovarian reservation and in vitro fertilization stimulation cycle outcomes in DOR participants. This pilot phase study investigated the impact of in vitro activation (IVA) on ovarian reservation and in vitro fertilization outcome in 10 infertile women with DOR from May to December 2023 at Taleghani Infertility Center, Tehran, Iran. Participants underwent general surgery and laparoscopy, involving the removal of a portion of one ovary, immediate transfer to the laboratory, dissection into small cubes, and subsequent re-implantation into the cases's ovary. The primary outcomes, include the count of retrieved oocytes, the number of oocytes reaching metaphase, and the secondary outcomes were the quantity and the number of embryos transferred, implantation rate, and occurrence of clinical pregnancy. The study revealed a significant increase in the antral follicle count before and after IVA (p = 0.033). Before IVA, the median estradiol level was 93.5 (57.0), which reduced to 79.0 (35.0) after IVA, indicating a statistically significant difference. On average, 2.3 (0.8) oocytes were retrieved, among which 1.5 (0.7) were metaphase II oocytes. The observed pregnancy rate among the 2 cases was 22.2%. The current study suggests that IVA may positively impact follicular growth and pregnancy outcomes among women with DOR.

Voxelated bioprinting of modular double-network bio-ink droplets

Analogous of pixels to two-dimensional pictures, voxels—in the form of either small cubes or spheres—are the basic building blocks of three-dimensional objects. However, precise manipulation of viscoelastic bio-ink voxels in three-dimensional space represents a grand challenge in both soft matter science and biomanufacturing. Here, we present a voxelated bioprinting technology that enables the digital assembly of interpenetrating double-network hydrogel droplets made of polyacrylamide/alginate-based or hyaluronic acid/alginate-based polymers. The hydrogels are crosslinked via additive-free and biofriendly click reaction between a pair of stoichiometrically matched polymers carrying norbornene and tetrazine groups, respectively. We develop theoretical frameworks to describe the crosslinking kinetics and stiffness of the hydrogels, and construct a diagram-of-state to delineate their mechanical properties. Multi-channel print nozzles are developed to allow on-demand mixing of highly viscoelastic bio-inks without significantly impairing cell viability. Further, we showcase the distinctive capability of voxelated bioprinting by creating highly complex three-dimensional structures such as a hollow sphere composed of interconnected yet distinguishable hydrogel particles. Finally, we validate the cytocompatibility and in vivo stability of the printed double-network scaffolds through cell encapsulation and animal transplantation.

Laser Powder Bed Fusion and Heat Treatment of the Martensitic Age‐Hardenable Steel (1.2709)

The primary objective of this study is to clarify the fundamental question of whether, in principle, it is possible to dispense with a prior solution annealing process in favor of a direct aging heat treatment for specimens of maraging stainless steel grade X3NiCoMoTi18‐9‐5 (1.2709) produced by laser powder bed fusion (LPBF). The waiver of a solution annealing process would significantly increase the process efficiency and thus support a sustainable and resource‐friendly production of such components. Therefore, the hardness, microstructure, and the present phases of specimens in as‐built + aged condition (AB + A) and solution‐annealed + aged (SOL + A) are examined during this study. Initially, an extended parameter study is performed using a Renishaw AM 250 LPBF system equipped with a pulsed mode laser system to achieve the highest possible apparent density. As test specimens, small cubes are produced for parameter study and are analyzed for porosity by means of optical microscopy. To investigate the relationship between microstructure and hardness in different material states, one series of specimens is aged directly after LPBF processing in the as‐built state (AB + A). For comparison, the other series was solution annealed at 820 °C for 60 min, quenched in water and then aged (SOL + A). A maximum hardness value of 614 HV1.0 is achieved for specimen aged at 490 °C for 120 min in as built condition (AB + A), while 624 HV1.0 was measured for specimen aged at 490 °C for 180 min in conventionally solution annealed + aged (SOL + A) condition. Significant austenite reversion is not observed at aging temperature of 490 °C in both cases. Aging of specimens at temperatures of 540 and 600 °C resulted in reduction of specimen hardness due to higher percentage of austenite reversion. No significant difference between the hardness values of AB + A and SOL + A specimens is observed. It can therefore be concluded that, in principle, conventional solution annealing and ageing can be dispensed with in favor of direct aging. However, as the results are based on small sized specimens, further investigations into the scalability are needed.

Enhancing Photocatalytic Activities for Sustainable Hydrogen Evolution on Structurally Matched CuInS2/ZnIn2S4 Heterojunctions.

Effective charge separation and migration pose a critical challenge in the field of solar-driven hydrogen production. In this work, a Z-scheme structured CuInS2/ZnIn2S4 heterojunction was successfully fabricated through a two-step hydrothermal synthesis method to significantly enhance the efficiency of solar-to-hydrogen energy conversion. Structural characterization revealed that the lattice-matched CuInS2/ZnIn2S4 heterojunction exhibits an enlarged interfacial contact area, which facilitates the transfer and separation of photogenerated charges. Microscopic analysis indicated that the CuInS2/ZnIn2S4 composite material has a tightly interwoven interface and a morphology resembling small sugar cubes. Photoelectrochemical spectroscopy analysis demonstrated that the heterojunction structure effectively enhances visible light absorption and charge separation efficiency, leading to an improvement in photocatalytic activity. Hydrogen production experimental data indicated that the CuInS2/ZnIn2S4 heterojunction photocatalyst prepared with a CuInS2 content of 20 wt% exhibits the highest hydrogen evolution rate, reaching 284.9 μmol·g-1·h-1. Moreover, this photocatalyst maintains robust photocatalytic stability even after three consecutive usage cycles. This study demonstrated that the Z-scheme CuInS2/ZnIn2S4 heterojunction photocatalyst exhibits enhanced hydrogen evolution efficiency, offering an effective structural design for harnessing solar energy to obtain hydrogen fuel. Therefore, this heterojunction photocatalyst is a promising candidate for practical applications in solar hydrogen production.

Impact of maturity level and geometric cuts of natural cheese on processed cheese product functionality

The study aimed to see the effect of maturity and different geometric cuts of Cheddar cheeses on processed cheese products (PCP) functional properties. Four Cheddar cheeses (mild, medium, sharp, and extra-sharp) were selected to manufacture PCP. The PCP made using extra-sharp Cheddar was soft and had higher meltability. The G′ and G″ values of mild and extra-sharp Cheddar PCP observed a similar trend, whereas medium and sharp Cheddar PCP followed a similar trend. In study 2, different geometric cuts, small cubes (SC), large cubes (LC), thin shreds (TN), and thick shreds (TK) of medium (M) and extra-sharp (ES) Cheddar cheese were used for PCP manufacture. The PCP with ES shreds (TN and TK) had higher meltability. The PCP with ES-TK was softer. In conclusion, maturation and geometric cuts significantly impacted the product's functionality. Manufacturers should select proper cutting equipment to extract full functional benefits and possibly reduce emulsifying salt usage.

Three-dimensional ultrastructural and anatomical analysis of prostatic neuroendocrine cells in mice.

A few studies have examined the ultrastructure of prostatic neuroendocrine cells (NECs), and no study has focused on their ultrastructure in three dimensions. In this study, three-dimensional ultrastructural analysis of mouse prostatic NECs was performed to clarify their anatomical characteristics. Three 13-week-old male C57BL/6 mice were deeply anesthetized, perfused with physiological saline and 2% paraformaldehyde, and then placed in 2.5% glutaraldehyde in 0.1 M cacodylate (pH 7.3) buffer for electron microscopy. After perfusion, the lower urinary tract, which included the bladder, prostate, coagulation gland, seminal vesicle, upper vas deferens, and urethra, was removed, and the specimen was cut into small cubes and subjected to postfixation and en bloc staining. Three-dimensional ultrastructural analysis was performed on NECs, the surrounding cells, tissues, and nerves using focused ion beam/scanning electron microscope tomography. Twenty-seven serial sections were used in the present study, and 32 mouse prostatic NECs were analyzed. Morphologically, the NECs could be classified into three types: flask, flat, and closed. Closed-shaped NECs were always adjacent to flask-shaped cells. The flask-shaped and flat NECs were in direct contact with the ductal lumen and always had microvilli at their contact points. Many of the NECs had accompanying nerves, some of which terminated on the surface in contact with the NEC. Three-dimensional ultrastructural analysis of mouse prostatic NECs was performed. These cells can be classified into three types based on shape. Novel findings include the presence of microvilli at their points of contact with the ductal lumen and the presence of accompanying nerves.

Rapid Construction of Double Crystalline Prussian Blue Analogue Hetero-Superstructure.

The controllable construction of complex metal-organic coordination polymers (CPs) merits untold scientific and technological potential, yet remains a grand challenge of one-step construction and modulating simultaneously valence states of metals and topological morphology. Here, a thiocyanuric acid (TCA)-triggered strategy is presented to one-step rapid synthesis a double-crystalline Prussian blue analogue hetero-superstructure (PBA-hs) that comprises a Co3[Fe(CN)6]2 cube overcoated with a KCo[Fe(CN)6] shell, followed by eight self-assembled small cubes on vertices. Unlike common directing surfactants, TCA not only acts as a trigger for the fast growth of KCo[Fe(CN)6] on the Co3[Fe(CN)6]2 phase resulting in a PBA-on-PBA hetero-superstructure, but also serves as a flange-like bridge between them. By combining experiments with simulations, a deprotonation-induced electron transfer (DIET) mechanism is proposed for formation of second phase in PBA-hs, differing from thermally and photo-induced electron transfer processes. To prove utility, the calcined PBA-hs exhibits enhanced oxygen evolution reaction performance. This work provides a new method to design of novel CPs for enriching chemistry and material science. This work offers a practical approach to design novel CPs for enriching chemistry and material science.

RETRACTED: Effect of derivatization method (KOH and BF3) on fatty acid profile data of boiled Tetracarpidium conophorum, and egusi pudding oils

Fatty acids are present in many foods, either free or esterified. Their presence helps to characterize and classify the food. The nature of these fatty acids is also associated with the treatments applied. To assess the fatty acid profile of these matrices, extractions are carried out using different solvents that influence the nature and lipid profile. The subsequent derivatization of fatty acids to more volatile fatty acyl methyl esters (FAMEs) prior to determination of the fatty acid profile takes into account the nature of the extraction solvent. Thus, the present work proposes to determine the fatty acid profile by Gas Chromatography Flame Ionisation Detector (GC-FID) of two lipid extracts derivatized by the MeOH/KOH and Hexane/MeOH/MeOH-BF3 procedures. Freshly harvested Tetracarpidium conophorum nuts from fields in the Fombap locality were brought to the laboratory where they were boiled (95 °C; 30 min), shelled, cut into small cubes and dried for 48 h at 45 °C. The dried seeds were ground and the resulting paste macerated in hexane for 48 h. The liquid fraction obtained was concentrated using a rotavapor, and the lipid extracts were stored at -15 °C. The egusi pudding was obtained by mixing 100 g of egusi seed paste with 0.50 g of white Piper nigrum powders, then packed in bulrush leaves and steamed for 120 min. After cooking, the product was stored for 4 days at room temperature and reheated twice a day. At the end of the last day, the lipid fraction oil was extracted following the methodology of Bligh and Dyer [1], then concentrated and preserved as before. The lipid extracts were then methylated using MeOH/KOH and Hexane/MeOH/MeOH-BF3 methods before injection into a GC-FID equipped with a Stabil Wax®-DA column. Supelco's standard mix of 37 FAMEs was used to identify and quantify the fatty acids present in the various samples. The results obtained enable us to identify the different fatty acids according to the retention time of their corresponding FAMEs and to quantify them. The fatty acids obtained were classified as saturated and unsaturated (mono and polyunsaturated). These analyses showed that the rapid derivatization method (MeOH/KOH) identified the same number of fatty acids as the Hexane/MeOH/MeOH-BF3 method in the lipid extract from the egusi pudding, whereas the Hexane/MeOH/MeOH-BF3 method identified four more fatty acids in the lipid extract coming from Tetracarpidium conophorum. Although the number of fatty acids was similar, the derivatization method influenced the nature of the fatty acids in the egusi pudding lipid extract. Overall, polyunsaturated fatty acids were the most abundant in the different oils. Omega-3 were the majority subclass in Tetracarpidium conophorum nuts, while omega-6 were in egusi pudding. The derivatization method did not influence the majority fatty acid (alpha linolenic) in Tetracarpidium conophorum nuts, whereas derivatization with BF3 gave trans linoleic and KOH cis linoleic in egusi pudding. These results show that the choice of derivatization method for fatty acid profiling and quantification is very important and depends on the technique and extraction solvents used.

Process qualification, additive manufacturing, and postprocessing of a hydrogen peroxide/kerosene 6 kN aerospike breadboard engine

This contribution addresses the complete process chain of an annular aerospike breadboard engine fabricated by laser powder bed fusion using the nickel-based superalloy Inconel® 718. In order to qualify the material and process for this high-temperature application, an extensive material characterization campaign including density and roughness measurements, as well as tensile tests at room temperature, 700, and 900 °C, was conducted. In addition, various geometric features such as triangles, ellipses, and circular shapes were generated to determine the maximum unsupported overhang angle and geometrical accuracy. The results were taken into account in the design maturation of the manifold and the cooling channels of the aerospike breadboard engine. Postprocessing included heat treatment to increase mechanical properties, milling, turning, and eroding of interfaces to fulfill the geometrical tolerances, thermal barrier coating of thermally stressed surfaces for better protection of thermal loads, and laser welding of spike and shroud for the final assembly as well as quality assurance. This contribution goes beyond small density cubes and tensile samples and offers details on the iterations necessary for the successful printing of large complex shaped functional parts. The scientific question is how to verify the additive manufacturing process through tensile testing, simulation, and design iterations for complex geometries and reduce the number of failed prints.

Modern narrative structure in animated short films: a tool to increase suspense

Classical narrative structure introduces specific principles and features to keep the audience engaged with the film. Modern, nonlinear narrative structures, however, provide their own techniques and tools in this sense. They can be utilized in animated short films to develop anticipation and suspense. The majority of animated short films are still focusing on classical narrative principles which only allows chronological order of time and sequence of events. Yet, a considerable potential of applying various nonlinear structures can be addressed when it comes to modern storytelling in animation. Consequently, filmmakers are able to increase suspense by solely adopting such variations. This paper discusses nonlinear narrative structures in five animated short films, “If anything happens I love you” (2021), “Alma” (2009), “Skhizein” (2008), “The house of small cubes” (2008) and “Maestro” (2005), and the way they suggest increased suspense by deviating from classical narrative principles. The present paper explains such potential by relying on David Bordwell theories, where he put an emphasis on important aspects of nonlinear narratives such as time, order, duration and frequency in particular. This paper argues that not only applying nonlinear structures are viable in the context of animated short films, different variations can be utilized as a powerful, innovative and beneficial tool in order to grab and hold the audience’s attention without having to concentrate on an excessively complicated timeline in the story.

Learned Tensor Neural Network Texture Prior for Photon-Counting CT Reconstruction.

Photon-counting computed tomography (PCCT) reconstructs multiple energy-channel images to describe the same object, where there exists a strong correlation among different channel images. In addition, reconstruction of each channel image suffers photon count starving problem. To make full use of the correlation among different channel images to suppress the data noise and enhance the texture details in reconstructing each channel image, this paper proposes a tensor neural network (TNN) architecture to learn a multi-channel texture prior for PCCT reconstruction. Specifically, we first learn a spatial texture prior in each individual channel image by modeling the relationship between the center pixels and its corresponding neighbor pixels using a neural network. Then, we merge the single channel spatial texture prior into multi-channel neural network to learn the spectral local correlation information among different channel images. Since our proposed TNN is trained on a series of unpaired small spatial-spectral cubes which are extracted from one single reference multi-channel image, the local correlation in the spatial-spectral cubes is considered by TNN. To boost the TNN performance, a low-rank representation is also employed to consider the global correlation among different channel images. Finally, we integrate the learned TNN and the low-rank representation as priors into Bayesian reconstruction framework. To evaluate the performance of the proposed method, four references are considered. One is simulated images from ultra-high-resolution CT. One is spectral images from dual-energy CT. The other two are animal tissue and preclinical mouse images from a custom-made PCCT systems. Our TNN prior Bayesian reconstruction demonstrated better performance than other state-of-the-art competing algorithms, in terms of not only preserving texture feature but also suppressing image noise in each channel image.

Papaia fermentada: estratégias para monitorizar e melhorar a fermentação das amostras - estudo preliminar

Introduction: Fermented papaya is known as a nutraceutical, with a unique composition and several health benefits. Its fermentation, being a central process of metabolism, converts the sugars in the fruit into alcohols or acids, with the intermediate formation of pyruvic acid. However, there is a lack of control and uniformity in terms of processes. Objectives: Carry out fermentation cycles of papaya in order to determine which conditions contribute to improving the pyruvic acid content and verify if there is any change of it after freezing preservation. Methodology: The papaya was washed with distilled water and cut into small cubes. About a quarter of each fruit was divided into two sterile flasks, adding ultrapure water, and placing it at 30°C. The flasks were manually shaken every 24 hours, an aliquot was taken for pH measurement. At the end of each fermentation cycle, the sample was subjected to centrifugation followed by gravity filtration and storage at -20°C. At the time of analysis, the aliquots were thawed, and the pH was measured again. The sodium pyruvate content (sodium salt of pyruvic acid) was quantified through a method adapted from another study and validated by this research team. The various fermentation cycles were carried out in duplicate, with changes in the fermentation conditions. Results: The highest content of sodium pyruvate was obtained at the end of the fermentation cycle where the whole fruit (pulp, peel and seeds) was used with sucrose supplementation (1 g.L-1). This indicates that the peel and seeds of papaya, due to their phytochemical composition, have constituents that improve the fermentation process while reducing food waste. The lowest content of sodium pyruvate was obtained on the second day of the fermentation cycle where only fresh papaya pulp and seeds were used, confirming that the presence of the peel is fundamental, probably due to the existence of autochthonous flora in the fruit that contributes to the fermentation process. Furthermore, it was also possible to verify that the pH does not change with the freezing process, indicating that there was no alteration of the pyruvic acid content during the preservation period. Conclusion: It was found that the fermentation conditions that promote a higher content of pyruvic acid is using the whole fruit and sucrose, at 30°C, for 7 days. However, other temperatures, as well as other fermentation conditions, should still be tested in order to understand if the fermentation process can be improved.

On the limitations of small cubes as test coupons for process parameter optimization in laser powder bed fusion of metals

The capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion process. Development of material and machine specific process parameters is commonly based on the results acquired from small cubic test coupons of ∼10 mm edge length. Such cubes are usually used to conduct the optimization of process parameters to produce dense materials. The parameters are then taken as the basis for the manufacturing of real part geometries. However, complex geometries go along with complex thermal histories during the manufacturing process, which can significantly differ from thermal conditions prevalent during the production of simply shaped test coupons. This may lead to unexpected and unpredicted local inhomogeneities of the microstructure and defect distribution in the final part, and it is a root cause of reservations against the use of additive manufacturing for the production of safety relevant parts. In this study, the influence of changing thermal conditions on the resulting melt pool depth of 316L stainless steel specimens is demonstrated. A variation in thermographically measured intrinsic preheating temperatures was triggered by the alteration of interlayer times and a variation in cross-sectional areas of specimens for three distinct sets of process parameters. Correlations between the preheating temperature, the melt pool depth, and occurring defects were analyzed. The limited expressiveness of the results of small density cubes is revealed throughout the systematic investigation. Finally, a clear recommendation to consider thermal conditions in future process parameter optimizations is given.

Level Kemampuan Penalaran Spasial Siswa SMA dengan Gaya Belajar Visual dalam Menyelesaikan Masalah Geometri

The purpose of this study is to describe the level of spatial reasoning ability of high school students with a visual learning style in solving geometric problems. This research is a qualitative descriptive study. The subjects in this study were two students with a visual learning style category which was determined based on a learning style questionnaire. Data collection techniques in this study used a learning style questionnaire, TKPS, and interviews. Researchers also used data analysis techniques according to Milles & Huberman, namely data reduction, data presentation, and conclusion. Meanwhile, to check the validity of the data researcher uses source triangulation. Based on the research data obtained, it was shown that the subject imagined the design of the drawing model into real objects such as a swimming pool with stairs and a warehouse with piles of cardboard so that the subject was able to convert two-dimensional icons into three-dimensional objects. The subject showed that in the model design, there were images of blocks that had length, width, and height and there were small cubes arranged so that the subject was able to make the correct relationship between two-dimensional icons to become three-dimensional objects. The subject also determines how many unit cubes are needed to fill the block by first calculating the volume of the block and then subtracting the total number of unit cubes in the block. Thus the visual subject's spatial reasoning in solving geometric problems is included in the category of high-level (spatial) spatial reasoning.

Comparing Performance and Preference of Visually Impaired Individuals in Object Localization: Tactile, Verbal, and Sonification Cueing Modalities

Audio guidance is a common means of helping visually impaired individuals to navigate, thereby increasing their independence. However, the differences between different guidance modalities for locating objects in 3D space have yet to be investigated. The aim of this study was to compare the time, the hand’s path length, and the satisfaction levels of visually impaired individuals using three automatic cueing modalities: pitch sonification, verbal, and vibration. We recruited 30 visually impaired individuals (11 women, average age 39.6 ± 15.0), who were asked to locate a small cube, guided by one of three cueing modalities: sonification (a continuous beep that increases in frequency as the hand approaches the cube), verbal prompting (“right”, “forward”, etc.), and vibration (via five motors, attached to different locations on the hand). The three cueing modalities were automatically activated by computerized motion capture systems. The subjects separately answered satisfaction questions for each cueing modality. The main finding was that the time to find the cube was longer using the sonification cueing (p = 0.016). There were no significant differences in the hand path length or the subjects’ satisfaction. It can be concluded that verbal guidance may be the most effective for guiding people with visual impairment to locate an object in a 3D space.

Kemampuan Spasial Dalam Menyelesaikan Soal Geometri

This research includes qualitative research. This research aims to determine spatial abilities in solving flat-sided geometric shape problems. The trial respondents in this research were 3 students in class IX9 of SMP Negeri 1 Parepare. The spatial ability assessment consists of a test sheet and an interview guide sheet. The spatial abilities produced in this research are indicated to meet the spatial ability indicators. Data analysis in this research went through data reduction, data presentation, and concluding/verification. The research results show that students show spatial abilities (1) Able to compare or connect cubes with blocks. (2) Knowing the number of small cubes that can fill the block. (3) Know how to calculate the volume of the beam.

A Dynamic Model of Human Limb Selection

Two experiments and a dynamic model forhuman limb selection are reported. In Experiment 1, left-handed and right-handed participants (N = 36) repeatedly used one hand for grasping a small cube. After a clear switch in the cube’s location, perseverative limb selection was revealed in both handedness groups. In Experiment 2, the cubes were presented in a clockwise and counter-clockwise sequence to right-handed participants (N = 15). A spatial shift in the switch point between right-hand use and left-hand use was observed. The model simulates the experiments by implementing the nonlinear multiple-timescale dynamics of the action-selection process underlying limb selection. It integrates two mechanisms that were earlier proposed to underlie this selection aspect of manual activity: limb dominance and attentional information. Finally, the model is used to simulate an influential earlier experiment, by establishing a conceptual link between cross-lateral inhibition asymmetry and the direction and strength of handedness.