Homogeneous Target Research Articles

Effect of coarse aggregates on contact explosion resistance of concrete—A mesoscopic investigation

Effect of coarse aggregates on contact explosion resistance of concrete—A mesoscopic investigation

Killing of xenogenous and virally infected homogenous target cells by shrimp lymphocyte-like haemocytes

Haemocytes play a crucial role in the invertebrate's immune system. In our lab, five subpopulations of shrimp haemocytes were identified in the past: hyalinocytes, granulocytes, semi-granulocytes and two subpopulations of non-phagocytic cells. In the latter two subpopulations, their characteristics such as having small cytoplasmic rims and not adhering to plastic cell-culture plates are very similar to those of mammalian lymphocytes. Therefore, they were designated lymphocyte-like haemocytes. Although little is known about their function, we hypothesize, based on their morphology, that they may have a cytotoxic activity like natural killer cells, with the ability to recognize and kill target cells. In our study, K562cells and Sf9 cells were used as xenogenous target cells to detect the cytotoxic activity of the shrimp non-adherent lymphocyte-like haemocytes. Non-adherent haemocytes were collected and mixed with K562cells and Sf9 cells at a 5:1 ratio and the binding activity was examined under a microscope. The binding rate of non-adherent haemocytes to K562cells and Sf9 cells reached 6.6% and 2.4% after 240min of culture, respectively. Then, the killing activity of non-adherent haemocytes was detected by an EMA staining (fluorescence microscopy), which showed 3.75% dead K562cells and 1.025% dead Sf9 cells, and by Sytox® blue staining (flow cytometry), which showed 4.97% of dead K562cells. Next, a killing assay was developed to visualize the killing activity of shrimp non-adherent haemocytes. Non-adherent haemocytes were pre-labeled in blue (CellTracker blue) and K562/Sf9 cells in green (CFSE); dead cells were differentially stained red with ethidium bromide. The cytotoxic activity increased and reached a level of 2.59% in K562cells and 0.925% in Sf9 cells at 120min after co-culture. Furthermore, in the co-cultures of non-adherent haemocytes with K562cells and Sf9 cells, upregulation of the gene and protein expression of the cytotoxic molecules torso-like protein and granzyme B was observed by RT-qPCR at 240min and western blotting at 180min. Additionally, non-adherent haemocytes were co-cultured with WSSV-inoculated shrimp ovary and lymphoid organ cells to detect the cytotoxicity to homogenous target cells. The binding activity started at 60min in both the ovary and lymphoid organ cultures and reached at 240min 50.62% and 40.7%, respectively. The killing activity was detected by EMA staining and the percentage of dead ovary and lymphoid organ cells increased respectively from 10.84% to 6.89% at 0min to 13.09% and 8.37% at 240min. In conclusion, we demonstrated the existence of cytotoxic activity of shrimp lymphocyte-like haemocytes against xenogenous cells from mammals and insects and against WSSV-infected homogenous shrimp cells.

Curving expectations: The minimal impact of structural curvature in biological puncture mechanics.

Living organisms have evolved various biological puncture tools, such as fangs, stingers, and claws, for prey capture, defense, and other critical biological functions. These tools exhibit diverse morphologies, including a wide range of structural curvatures, from straight cactus spines to crescent-shaped talons found in raptors. While the influence of such curvature on the strength of the tool has been explored, its biomechanical role in puncture performance remains untested. Here, we investigate the effect of curvature on puncture mechanics by integrating experiments with finite element simulations. Our findings reveal that within a wide biologically relevant range, structural curvature has a minimal impact on key metrics of damage initiation or the energies required for deep penetration in isotropic and homogeneous target materials. This unexpected result improves our understanding of the biomechanical pressures driving the morphological diversity of curved puncture tools and provides fundamental insights into the crucial roles of curvature in the biomechanical functions of living puncture systems.

Monte Carlo dosimetric analyses on the use of 90Y-IsoPet intratumoral therapy in canine subjects

Objective. To investigate different dosimetric aspects of 90Y-IsoPet™ intratumoral therapy in canine soft tissue sarcomas, model the spatial spread of the gel post-injection, evaluate absorbed dose to clinical target volumes, and assess dose distributions and treatment efficacy. Approach. Six canine cases treated with 90Y-IsoPet™ for soft tissue sarcoma at the Veterinary Health Center, University of Missouri are analyzed in this retrospective study. The dogs received intratumoral IsoPet™ injections, following a grid pattern to achieve a near-uniform dose distribution in the clinical target volume. Two dosimetry methods were performed retrospectively using the Monte Carlo toolkit OpenTOPAS: imaging-based dosimetry obtained from post-injection PET/CT scans, and stylized phantom-based dosimetry modeled from the planned injection points to the gross tumor volume. For the latter, a Gaussian parameter with variable sigma was introduced to reflect the spatial spread of IsoPet™. The two methods were compared using dose-volume histograms (DVHs) and dose homogeneity, allowing an approximation of the closest sigma for the spatial spread of the gel post-injection. In addition, we compared Monte Carlo-based dosimetry with voxel S-value (VSV)-based dosimetry to investigate the dosimetric differences. Main results. Imaging-based dosimetry showed differences between Monte Carlo and VSV calculations in tumor high-density areas with higher self-absorption. Stylized phantom-based dosimetry indicated a more homogeneous target dose with increasing sigma. The sigma approximation of the 90Y-IsoPet™ post-injection gel spread resulted in a median sigma of approximately 0.44 mm across all cases to reproduce the dose heterogeneity observed in Monte Carlo calculations. Significance. The results indicate that dose modeling based on planned injection points can serve as a first-order approximation for the delivered dose in 90Y-IsoPet™ therapy for canine soft tissue sarcomas. The dosimetry evaluation highlights the non-uniformity of absorbed doses despite the gel spread, emphasizing the importance of considering tumor dose heterogeneity in treatment evaluation. Our findings suggest that using Monte Carlo for dose calculation seems more suitable for this type of tumor where high-density areas might play an important role in dosimetry.

One-Pot Detection of Proteins Using a Two-Way Extension-Based Assay with Cas12a.

Protein biomarkers are an important class of biomarkers in disease diagnosis and are traditionally detected by enzyme-linked immunosorbent assay and mass spectrometry, which involve multiple steps and a complex workflow. In recent years, many CRISPR-Cas12a-based methods for protein detection have been developed; however, most of them have not overcome the workflow complications observed in traditional assays, limiting their applicability in point-of-care testing. In this work, we designed a single-step, one-pot, and proximity-based isothermal immunoassay integrating CRISPR Cas12a for homogeneous protein target detection with a simplified workflow and high sensitivity. Probes consisting of different binders (small molecule, aptamer, and antibody) conjugated with oligonucleotides undergo two-way extension upon binding to the protein targets, leading to downstream DNA amplification by a pair of nicking enzymes and polymerases to generate target sequences for Cas12a signal generation. We used the streptavidin-biotin model to demonstrate the design of our assay and proved that all three elements of protein detection (target protein binding, DNA amplification, and Cas12a signal generation) could coexist in one pot and proceed isothermally in a single buffer system at a low reaction volume of 10 μL. The plug-and-play applicability of our assay has been successfully demonstrated using four different protein targets, streptavidin, PDGF-BB, antidigoxigenin antibody, and IFNγ, with the limit of detection ranging from fM to pM.

Socioeconomic Factors Driving the Transition to a Low-Carbon Energy System

Citizen participation via different investment schemes may be a promising solution to the financing barriers inhibiting energy transition. In this regard, citizens may be approached as potential investors in renewables, but, to mobilize their capital, strategies need to be developed. Much like other services or products seeking to improve their market position, renewable energy investments by citizens also require dedicated efforts to acquire a strong market position. Using a large sample of Greek citizens, this study investigated whether it is possible to identify distinct and addressable citizen clusters which can enable energy developers and marketers to effectively address the preferences and needs of potential investor segments. The performance of k-means cluster analysis identified four clusters: Indifferent Investors were neither driven by economic or social factors, Enthusiastic Investors were motivated both by economic and social factors, Pro-environmental Investors were driven by the environmental benefits, and Social Investors were motivated by the social aspects of the investment. Moreover, each cluster demonstrated different levels of willingness-to-invest in renewable energy and were knowledge about renewable energy investments. It was concluded that citizens should not be approached as a homogeneous target group by marketing experts and policymakers, while novel strategies should be followed.

Comparative Dosimetric Analysis of IMRT and VMAT in Head and Neck Cancers

Purpose: The aim of study was to dosimetrically evaluate and compare IMRT and VMAT plans for irradiation of local head and neck cancers focusing on target coverage, conformity index, homogeneity index and dose perceived by the organs at risk (OAR). Methods: Prospective study conducted on 50 patients selected randomly and divided in two groups in which one group receive IMRT plan and another received VMAT plan. Results: PTV coverage was similar for both the techniques. The conformity index was higher for VMAT in comparison to IMRT which is statistically significant. The homogeneity index was also better in VMAT plans as compared to IMRT except for higher PTV volume where IMRT had better plans. The mean dose to parotid were significantly lesser in parotid glands in VMAT plans. Also, the point max dose to spinal cord, brainstem, vestibulocochlear nerve was lesser. There was no significant difference in dose received by spinal cord in both arms. Conclusion: VMAT provides better dose conformity, more homogenous target coverage and OAR sparing in comparison to IMRT.

Evaluation of Upscaling the Selective Electrophoretic Deposition of Reduced Graphene Oxide on Miniaturized Au Interdigital Electrodes from Chip-to Wafer-Level

Today’s novel materials challenge the research industry to enhance the performance and to reduce the power consumption of microchips as well as to develop new sensor principles. All this applies pressure on the investigation of new economical mass production technologies for the integration into standard process sequences or on top of state-of-the-art CMOS devices. Since the discovery of graphene in 2004, many different variations have been investigated, thus the number of publications of graphene-based content grew from a few in 2004 exponential to 1.2 million only in 2019, according to Google Scholar analysis. The deposition of graphene-based materials at wafer-level is still difficult to do economically on standard SEMI wafers up to 8” diameter. In this publication, the selective electrophoretic deposition (EPD) of reduced graphene oxide flakes (rGO) will be shown. This technique is a very promising deposition method for large scale fabrication. The EPD of rGO particles is the only known way to create 3D surface topologies for an enhanced sensing area of electrochemical sensor applications e.g. biosensors. The electrical and chemical properties of this novel material provides a broad range of applications for possible sensor solutions [1, 2]. Firstly, the deposition will be shown on chip scale to gain optimum parameters in suspension preparation and EPD deposition time/voltage for a uniform particle deposition over the sensor area. Shortcuts from particles between the transmission lines or co-deposition on reference electrodes have to be avoided. This leads to a high selectivity in rGO particle deposition on Au-structures. Afterwards designs and experiments have been made on array level and a proof of concept wafer-level deposition with a low volume suspension is demonstrated. In previous work, the adhesion of rGO on Au structures in electrochemical sensors with a liquid flow, showed a migration of the deposited particles with the friction of the liquid [3]. Therefore, standard separation of particle agglomeration or splitting of primary particles with ultra sonic sonotrodes are not sufficient to gain highly concentrated suspensions with homogenous target particle distributions (< 0,5µm ≤ 1µm ≥ 5µm). For this reason, a novel particle crushing preparation by ball milling is introduced and enhanced selectivity with an improved adhesion is demonstrated. A full process of the preparation of the colloidal suspension with the definition of target particle sizes with an optimum zeta potential will be provided and the cathodic electrophoretic deposition shown [4, 5]. For the evaluation of the deposition experiments, stereo microscopy is used to reveal the selectivity on the interdigital electrode (IDE) structures (sensor area) and scanning electron microscopy (SEM) analysis is used to characterize particle sizes and 3D topography, in terms of primary and secondary particles (agglomerates). For this study, IDE structures with 15 different geometry variations (3µm to 15µm lines and spaces) are used that were manufactured [6] to evaluate the rGO deposition on chip level. A novel multisensory array design with eight sensing areas are presented, combined with wafer-level deposition as a proof of concept on a 200mm wafer.

Establishing the function relationship between time spectrum and proton range in proton therapy through Monte Carlo simulation

To validate range shifts in proton therapy, we investigated the potential of using the temporal information of prompt gamma rays as an indicator. We simulated the proton transport process using Monte Carlo simulations and used a geometric scorer to obtain the location and timing of prompt gamma ray production. By using a homogeneous target material in the simulation model, we established a fitted relationship between the range of 90–210 MeV protons and the corresponding temporal spectral width. Additionally, by introducing air cavities of 2–20 mm in simulations of inhomogeneous target materials, we observed significant correlations between the range offsets and the temporal spectral widths. These correlations were fitted to derive a functional relationship between the two variables.

Comparison of skin dose in IMRT and VMAT with TrueBeam and Halcyon linear accelerator for whole breast irradiation

With the increasing use of flattening filter free (FFF) beams, it is important to evaluate the impact on the skin dose and target coverage of breast cancer treatments. This study aimed to compare skin doses of treatments using FFF and flattening filter (FF) beams for breast cancer. The study established treatment plans for left breast of an anthropomorphic phantom using Halcyon’s 6-MV FFF beam and TrueBeam’s 6-MV FF beam. Volumetric modulated arc therapy (VMAT) with varying numbers of arcs and intensity modulated radiation therapy (IMRT) were employed, and skin doses were measured at five points using Gafchromic EBT3 film. Each measurement was repeated three times, and averaged to reduce uncertainty. All plans were compared in terms of plan quality to ensure homogeneous target coverage. The study found that when using VMAT with two, four, and six arcs, in-field doses were 19%, 15%, and 6% higher, respectively, when using Halcyon compared to TrueBeam. Additionally, when using two arcs for VMAT, in-field doses were 10% and 15% higher compared to four and six arcs when using Halcyon. Finally, in-field dose from Halcyon using IMRT was about 1% higher than when using TrueBeam. Our research confirmed that when treating breast cancer with FFF beams, skin dose is higher than with traditional FF beams. Moreover, number of arcs used in VMAT treatment with FFF beams affects skin dose to the patient. To maintain a skin dose similar to that of FF beams when using Halcyon, it may be worth considering increasing the number of arcs.

Mapping m6A Sites on HIV-1 RNA Using Oligonucleotide LC-MS/MS.

The biological significance of chemical modifications to the ribonucleic acid (RNA) of human immunodeficiency virus type-1 (HIV-1) has been recognized. However, our understanding of the site-specific and context-dependent roles of these chemical modifications remains limited, primarily due to the absence of nucleotide-resolution mapping of modification sites. In this study, we present a method for achieving nucleotide-resolution mapping of chemical modification sites on HIV-1 RNA using liquid chromatography and tandem mass spectrometry (LC-MS/MS). LC-MS/MS, a powerful tool capable of directly analyzing native RNAs, has proven effective for mapping RNA modifications in small RNA molecules, including ribosomal RNA and transfer RNA. However, longer RNAs have posed challenges, such as the 9 Kb HIV-1 virion RNA, due to the complexity of and ambiguity in mass differences among RNase T1-cleaved RNA fragments in LC-MS/MS data. Here, we introduce a new target RNA enrichment method to isolate small local RNA fragments of HIV-1 RNA that potentially harbor site-specific N6-methyladenosine (m6A) modifications. In our initial trial, we used target-specific DNA probes only and encountered insufficient RNA fragmentation due to inefficient S1 digestion near the target site. Recognizing that inefficient S1 digestion by HIV-1 RNA is likely due to the formation of secondary structures in proximity to the target site, we designed multiple DNA probes annealing to various sites of HIV-1 RNA to better control the structures of RNA substrates for S1 digestion. The use of these non-target DNA probes significantly improved the isolation of more homogeneous target RNA fragments of approximately 50 bases in length. Oligonucleotide LC-MS/MS analysis of these isolated target RNA fragments successfully separated and detected both m6A-methylated and non-methylated oligomers at the two m6A-predicted sites. The principle of this new target enrichment strategy holds promise and should be broadly applicable to the analysis of any lengthy RNA that was previously deemed infeasible for investigation using oligonucleotide LC-MS/MS.

Kenya Psychosis-Risk Outcomes Study (KePROS): Development of an Accelerated Medicine Partnership Schizophrenia-Aligned Project in Africa.

The Accelerating Medicines Partnership Schizophrenia (AMP SCZ) funds a longitudinal study of 43 research sites across 5 continents to develop tools to stratify developmental trajectories of youth at clinical high risk for psychosis (CHR) and identify homogenous targets for future clinical trials. However, there are no sites in Africa, leaving a critical gap in our knowledge of clinical and biological outcomes among CHR individuals. We describe the development of the Kenya Psychosis-Risk Outcomes Study (KePROS), a 5-year NIH-funded project in Kenya designed to harmonize with AMP SCZ. The study will recruit over 100 CHR and 50 healthy participants and conduct multiple clinical and biomarker assessments over 2 years. Capacity building is a key component of the study, including the construction of an electroencephalography (EEG) laboratory and the upgrading of a local 3 T magnetic resonance imaging (MRI) machine. We detail community recruitment, study methodologies and protocols, and unique challenges with this pioneering research in Africa. This paper is descriptive only. Planned future analyses will investigate possible predictors of clinical outcomes and will be compared to results from other global populations. KePROS will provide the research community with a rich longitudinal clinical and biomarker dataset from an African country in the developing Global South, which can be used alongside AMP SCZ data to delineate CHR outcome groups for future treatment development. Training in mental health assessment and investment in cutting-edge biomarker assessment and other technologies is needed to facilitate the inclusion of African countries in large-scale research consortia.

Effects of urban expansion on the surrounding agricultural communities of the southern Ethiopian town of Jajura

ABSTRACT This study used a mixed research design for several reasons. Firstly, the researchers used longitudinal data from open-source remote sensing satellite imagery dating back at least 30 years to study urban expansion into rural farmland. Then, the researchers used cross-sectional data from household surveys, where data collection tools such as questionnaires and structured interviews were utilized. A simple sampling procedure was used to ensure the representativeness of homogeneous target group households. The survey data was analyzed with SPSS software, and the urban-to-farmland extent was investigated with Landsat satellite images and observation intervals every 10 years for the last 30 years. The key finding of this study was that urban expansion is encroaching onto farmland, negatively impacting household livelihoods. It is recommended that urban expansion should be managed and minimized and that cooperation with the communities in the study area is an important issue. The study emphasizes the significance of comprehending the implications of uncontrolled urban development on rural communities in Ethiopia, using a mixed research approach comprising both longitudinal and cross-sectional data. The research demonstrates that expanding cities are having a considerable impact on agricultural livelihoods and require delicate handling to mitigate their unfavorable influence.

Ballistic performance and mechanism of B4C/Al laminated targets with different configurations

Ballistic performance and mechanism of B4C/Al laminated targets with different configurations

The role of reference group influence: A benchmarking study with working and non-working groups

The role of reference group influence: A benchmarking study with working and non-working groups

Locoregional breast radiotherapy including IMN: optimizing the dose distribution using an automated non-coplanar VMAT-technique

Background Volumetric Modulated Arc Therapy (VMAT) offers better conformity, homogeneity and sparing of the heart and ipsilateral lung for locoregional radiotherapy in left-sided breast cancer compared to three-dimensional conformal radiotherapy (3D-CRT). However, conventional coplanar VMAT (cVMAT) can result in higher doses to the normal tissue on the contralateral side. This study investigates a non-coplanar VMAT-technique (ncVMAT) to mitigate this issue. Material and methods CT series of 20 left sided breast cancer patients were included for planning of locoregional breast radiotherapy including internal mammary nodes (IMN). Three treatment plans; 3D-CRT, cVMAT and ncVMAT, were generated for each patient with a prescription dose of 40.05 Gy in 15 fractions. Both VMAT-techniques consisted of a single arc in the axial plane, while ncVMAT included an additional arc in the sagittal plane. All plans were optimized to cover the clinical target volume (CTV) by 38.05 Gy for the breast and 36.05 Gy for lymph nodes, with as low as possible dose to organs at risk. Results Full CTV coverage was achieved for all plans. Both cVMAT and ncVMAT delivered more conformal and homogeneous target doses than 3D-CRT. Doses to the heart and ipsilateral lung were significantly lower with ncVMAT compared to both cVMAT and 3D-CRT. ncVMAT reduced doses to both the contralateral breast and lung compared to cVMAT and achieved levels similar to 3D-CRT for the contralateral breast and moderately higher doses for the contralateral lung. Delivery of high doses (>30 Gy) to the contralateral side was completely avoided with ncVMAT, contrary to the results for cVMAT and 3D-CRT. Conclusion ncVMAT reduced doses to the heart and ipsilateral lung as compared to both cVMAT and 3D-CRT. All contralateral dose metrics were reduced with the novel ncVMAT technique compared to cVMAT, and the mean contralateral breast doses were similar to 3D-CRT.

Reassessing the terminal ballistic performance of trilobate and quadrilobate arrow points on Iron Age battlefields.

In the Eurasian Iron Age arrow points comprise a prominent class of artifact. Projectile experiments are useful for studying the ballistic performance of ancient arrow points and implications of arrow point innovations in warfare and shifting socio politics in Eurasia. However, when projectile experiments are not representative of past weapon use, they can lead to misinterpretations of the archaeological record. Notable problems arise when homogeneous target simulants used in controlled experiments are not representative of the targets past weapons were designed to encounter. This article explores the relationship between arrow point morphology and design choices in the Iron Age using different target media. Shooting arrow points into pottery clay leads to the conclusion that more blades reduced penetrating performance on ancient battlefields, but a very different result obtains by shooting the same points into thick tooling leather as a simulant for leather body armor. The results help explain patterns observed in the Eurasian archaeological record, where trilobate arrow points-initially developed by lightly armored horse archers on the Eurasian steppe-were increasingly adopted by a wide range of societies across Eurasia throughout the Iron Age.

NO-sensitive guanylyl cyclase discriminates pericyte-derived interstitial from intra-alveolar myofibroblasts in murine pulmonary fibrosis

BackgroundThe origin of αSMA-positive myofibroblasts, key players within organ fibrosis, is still not fully elucidated. Pericytes have been discussed as myofibroblast progenitors in several organs including the lung.MethodsUsing tamoxifen-inducible PDGFRβ-tdTomato mice (PDGFRβ-CreERT2; R26tdTomato) lineage of lung pericytes was traced. To induce lung fibrosis, a single orotracheal dose of bleomycin was given. Lung tissue was investigated by immunofluorescence analyses, hydroxyproline collagen assay and RT-qPCR.ResultsLineage tracing combined with immunofluorescence for nitric oxide-sensitive guanylyl cyclase (NO-GC) as marker for PDGFRβ-positive pericytes allows differentiating two types of αSMA-expressing myofibroblasts in murine pulmonary fibrosis: (1) interstitial myofibroblasts that localize in the alveolar wall, derive from PDGFRβ+ pericytes, express NO-GC and produce collagen 1. (2) intra-alveolar myofibroblasts which do not derive from pericytes (but express PDGFRβ de novo after injury), are negative for NO-GC, have a large multipolar shape and appear to spread over several alveoli within the injured areas. Moreover, NO-GC expression is reduced during fibrosis, i.e., after pericyte-to-myofibroblast transition.ConclusionIn summary, αSMA/PDGFRβ-positive myofibroblasts should not be addressed as a homogeneous target cell type within pulmonary fibrosis.

Current Approach of Small Field Electron Beam for Head and Neck Cases

Regarding the increasing use of small-field photons in clinical treatment, in this study, we investigate the use of small-field electron beams in clinical treatment. This study aimed to evaluate small-field electron beam dosimetry of the nasopharyngeal, thyroid, and ethmoid sinus carcinoma cases. Dose measurement was done using EBT3 film. In nasopharyngeal cases with a homogenous area and irregular surface, the dose discrepancies for 6 MeV energy were unpredictable except for the 5×5 cm2 field size. For all energies in 5×5 cm2 field size, the dose discrepancies were less than 3%. In these cases, we found that a smaller electron beam field will increase the percentage of the dose discrepancy. This is caused by the effect of the lateral scatter disequilibrium in a small field electron beam. For ethmoid sinus cases, dose discrepancy depends on the field size and inhomogeneity of bone and tissue organ. Based on the evaluation of doses on the spinal cord, chiasm, and larynx (OAR), it can be seen that these organs received a very small dose. From this result, a small field electron beam is recommended for cases with a homogeneous target. However, in cases with a heterogenous target, further investigation is needed.

On the (Non-)Scalability of Target Media for Evaluating the Performance of Ancient Projectile Weapons

Abstract When they work, controlled experiments can efficiently and clearly reveal essential characteristics of the functions and performance of ancient hunting and fighting weapons. However, homogenous target media must be carefully validated to ensure that controlled tests capture the same variables that made weapons effective in their original application. Although homogenous flesh simulants have proven effective for studying firearms, the same simulants cannot be assumed to be effective when testing low-velocity cutting/piercing projectiles, which have significantly different performance characteristics than bullets. We build on past research showing that two flesh simulants that are commonly used by archaeologists, ballistics gelatin and pottery clay, fail to capture how atlatl darts and arrows perform when penetrating biological tissues. In accord with forensic research of knife-thrust attacks, natural and polymeric skin simulants may prove effective in future experiments, but this requires further research.