Adequate Choice Research Articles

Design of optimal concentrations for in vitro cytotoxicity experiments.

Concentration-dependent cytotoxicity experiments are frequently used in toxicology. Although it has been reported that an adequate choice of concentrations improves the quality of the statistical inference substantially, a recent literature review of three major toxicological journals has shown that the corresponding methods are rarely used in toxicological practice. In this study the performance of different sets of concentrations, also called designs, are analyzed, while the overall goal is to promote the advantages of optimal design procedures and to present a user-friendly guideline for planning new cytotoxicity concentration-response experiments. We compare the frequently used log-equidistant design to a Bayesian design, which is constructed by methods of optimum design theory. Using both a dense data set of concentration-cytotoxicity data of valproic acid (VPA) and regular assay data of 104 substances, the performance of the different designs is analyzed in two scenarios, where detailed previous knowledge on VPA is available or not. The results show that it is critical to apply a specific design strategy to determine optimal concentrations for cytotoxicity testing. In particular, the Bayesian design technique with and without incorporating pre-existing knowledge of a specific test substance resulted in a more precise statistical inference than the other used designs. Finally, we present a guideline for upcoming experiments and an accessible user-friendly Shiny app (see http://shiny.statistik.tu-dortmund.de:8080/app/occe ).

Rare forms of ectopic pregnancy in the rudimentary horn and ovary. How not to miss the main thing?

This article presents two cases of ectopic pregnancy in the ovary and rudimentary horn, which had a life-threatening course. Despite availability of modern high-quality diagnostics, determining the condition remains challenging, because the definitive diagnosis is established and confirmed only intraoperatively. Hence, the clinical picture can be used primarily in making a diagnosis and choosing an appropriate treatment strategy. Rare localizations, such as in the ovary and rudimentary horn, which cause difficulties in making a diagnosis, should not be overlooked. If an ectopic pregnancy is not detected promptly and the risks are underestimated, death may occur. Two clinical cases clearly demonstrate timely diagnosis, regardless of additional examination methods (e.g., pelvic ultrasound, human chorionic gonadotropin test), and adequate choice of access and scope of surgical intervention. Moreover, the lack of awareness among women about this type of pathology should be considered. Patients often do not complain, do not remember the date of their last menstruation, do not monitor their menstrual cycle, and do not seek medical help in a timely manner. The combination of several factors can lead to fatal events. In this study, both cases of ectopic pregnancy with a rare localization ended favorably.

Separation efficiency of a wastewater bar screen based on a 3D computational fluid dynamics modeling

The wastewater screening process is a crucial step in the majority of wastewater treatment plants, frequently using mechanical bar screens as the first filtration step to remove heavy debris from the wastewater flow. In the present study, two 3D geometries of bar screens with different screen openings were presented to investigate the effect of the variation in screen spacing of bars on the separation efficiency of debris. Based on the Ansys Fluent CFD code within the Eulerian-Lagrangian approach, the particle trajectories were tracked, and the retention efficiency of these two bar screens was evaluated. The results show that a higher particle separation efficiency is favored for small bar spacing and coarse particle sizes. Actually, despite the impact of bar spacing on the separation efficiency of particles, the adequate choice of this parameter is related to particle properties and the fluid flow inlet velocity. These parameters also have a great influence on the separation efficiency of bar screens. The study can help for more structural improvements in the shape of the screening media, which leads to enhanced performance of wastewater screening facilities.

Consideration of fuel and oxidizer combinations for mass and volume limited hybrid rocket motors

AbstractThis research considers different storable oxidizer and fuel combinations for hybrid propulsion, looking for the most adequate candidates for mass and volume limited systems. High specific impulse Isp is the main indication for minimum mass, whereas high density specific impulse ρIsp is a good measure for smaller volume. Other aspects such as safety, handling, toxicity, burn rate, hypergolicity, and the oxidizer to fuel O/F ratio, may affect the final choice of propellant ingredient combination. For mass‐limited systems hydrogen peroxide H2O2 or nitrogen tetroxide N2O4 (the latter is toxic and hard to handle) oxidizers give the best results with most solid fuels (mainly hydroxyl‐terminated polybutadiene HTPB). For volume‐limited systems the same combinations may apply; however, in that case polyester fuel may be an adequate choice as well because of its high density. Nitrous oxide N2O is the most inadequate oxidizer for volume‐limited systems, yielding ρIsp lower by about 40 % compared to other oxidizers. Reducing the structure and insulation mass may result from decreasing the high‐pressure, high‐temperature section (the combustion chamber) and can be achieved from high O/F combinations employing N2O or H2O2 oxidizers. N2O gives relatively safe system, H2O2 enables hypergolic combinations, HNO3 is good for long‐term storage, whereas paraffin wax and expandable graphite additive yield high fuel regression rate and thrust. Overall, H2O2 oxidizer seems optimal for many operational aspects, but it should be chemically stabilized to minimize decomposition.

Outage probability minimization by optimal beamwidth selection for UAV-to-HAP FSO links under pointing inaccuracies

The design of a free-space optical (FSO) link between an unmanned aerial vehicle (UAV) and a high-altitude platform (HAP) in the practical scenario of generalized pointing errors (PE) and beam wandering (BWAN) is addressed. We propose to select appropriately the system parameters such as optical beamwidth at the UAV and its flight altitude so as to minimize the outage probability. First, we characterize the channel statistics by taking into account the joint influence of attenuation loss, weak atmospheric turbulence and generalized PE particularly impaired by BWAN. Second, we formulate the closed-form expressions for outage probability, where we also derive an asymptotic expression at high signal-to-noise ratios (SNR)s. Third, we derive the optimum beamwidth at the UAV leading to the instantaneous minimum outage probability under generalized PE and BWAN. Finally, we address the optimal flight altitude of the UAV to avoid strong turbulence in order to ensure efficient data transmission. Our simulation results validate both the effectiveness and the accuracy of the derived asymptotic outage probability and the adequate choice of beamwidth and flight altitude to minimize the average outage performance. For instance, our results show that at an SNR of 20 dBm, the link availability is increased from 20% (with nominal beamwidth) to more than 70% by adopting the proposed beamwidth optimization.

P-711 Female age at embryo creation and embryo transfer do not impact the ongoing pregnancy rates in single euploid frozen embryo transfers

Abstract Study question Which factors influence the ongoing pregnancy rate in single euploid frozen embryo transfer (seFET) cycles? Summary answer Ongoing pregnancy rates in seFET cycles are significantly influenced by parity, BMI, embryo quality, trophectoderm biopsy day and endometrial preparation, but not by female age. What is known already The probability of a pregnancy is influenced by several factors and female age is the major determinant as the ovarian reserve decreases and embryo aneuploidy increases with age. Preimplantation genetic testing for aneuploidy and embryo selection was considered to mitigate the effect of female age on ART treatment outcomes by selecting euploid embryo(s) for embryo transfer (ET). Previously published data point to a decline in pregnancy rates with increased maternal age even when a euploid embryo is transferred. However, other factors besides embryo ploidy might play a role in the chance of achieving an ongoing pregnancy. Study design, size, duration Retrospective study, including 1923 women who underwent a seFET between 04/2017 and 08/2023. Patients’ (age at oocyte-pick-up and seFET, BMI, parity, endometrial preparation type) and embryo characteristics (Day of biopsy, embryo quality (EQ)) were considered for the analysis. Ongoing pregnancy was defined as viable pregnancy beyond 12 weeks of gestation. Participants/materials, setting, methods Women, undergoing a seFET either in a true natural cycle (NC) t or in a hormonal replacement cycle (HRT). Only cycles with embryos being biopsied on day 5 or day 6 and a known outcome of the cycle were included. Main results and the role of chance There were 990 (51.48%) ongoing pregnancies among 1923 included transfers. The ongoing pregnancy rates were 51.8%, 47.4%, 52.3% and 52.8% for women aged ≤35, >35 to ≤ 37, >37 to ≤ 40, and >40 years-old at seFET, respectively. Cochrane Armitage test did not show a significant trend for decreasing pregnancy rates with increasing female age at OPU (P = 0.679) or at transfer (P = 0.609). Multivariable regression analyses showed primiparous, and multiparous women were more likely to have an ongoing pregnancy compared to nulliparous women (OR: 2.96, 95%CI:2.22-3.94 and 2.73, 95%CI:2.10-3.55, respectively, P < 0.001 for both) and those who had a natural endometrial preparation (OR: 1.53, 95%CI: 1.24-1.88, P < 0.001). Transfers with good quality embryo had higher ongoing pregnancy rates compared to those who had a fair quality embryo (OR: 2.0, 95%CI: 1.37-2.91, P < 0.001). Being overweight or obese at the time of transfer were associated with lower ongoing pregnancy rates compared to normal weight (OR: 0.71, 95%CI: 0.56-0.89, and 0.68, 95%CI: 0.52-0.88, respectively, P = 0.003 for both). Age categories at the time of transfer did not show a significant effect on ongoing pregnancy rates in multivariable analyses (P > 0.05 for all) and there was no significant interaction between age at OPU and embryo quality categories either (P = 0.881 and 0.601). Limitations, reasons for caution The retrospective design of the study is a limitation. Wider implications of the findings This analysis did not confirm the otherwise reported negative impact of female age on the outcome of seFET cycles. Outcomes are significantly influenced by BMI, parity, EQ-related factors as well as the endometrial preparation. As BMI and endometrial preparation can be influenced, the adequate choice might improve seFET outcomes. Trial registration number not applicable

Reducing hardware requirements for entanglement distribution via joint hardware-protocol optimization

We conduct a numerical investigation of fiber-based entanglement distribution over distances of up to 1600 km using a chain of processing-node quantum repeaters. We determine minimal hardware requirements while simultaneously optimizing over protocols for entanglement generation and entanglement purification, as well as over strategies for entanglement swapping. Notably, we discover that through an adequate choice of protocols the hardware improvement cost scales linearly with the distance covered. Our results highlight the crucial role of good protocol choices in significantly reducing hardware requirements, such as employing purification to meet high-fidelity targets and adopting a swap as soon as possible policy for faster rates. To carry out this analysis, we employ an extensive simulation framework implemented with NetSquid, a discrete-event-based quantum-network simulator, and a genetic-algorithm-based optimization methodology to determine minimal hardware requirements.

Approximate Bayesian computation for inferring Waddington landscapes fromsingle-cell data.

Single-cell technologies allow us to gain insights into cellular processes at unprecedented resolution. In stem cell and developmental biology snapshot data allow us to characterize how the transcriptional states of cells change between successive cell types. Here, we show how approximate Bayesian computation (ABC) can be employed to calibrate mathematical models against single-cell data. In our simulation study, we demonstrate the pivotal role of the adequate choice of distance measures appropriate for single-cell data. We show that for good distance measures, notably optimal transport with the Sinkhorn divergence, we can infer parameters for mathematical models from simulated single-cell data. We show that the ABC posteriors can be used (i) to characterize parameter sensitivity and identify dependencies between different parameters and(ii) to construct representations of the Waddington or epigenetic landscape, which forms a popular and interpretable representation of the developmental dynamics. In summary, these results pave the way for fitting mechanistic models of stem cell differentiation to single-cell data.

Pointing correction based on limit cycles oscillators applied on a heliostats field digital twin

Digital twin models are an emerging topic that captures the dynamic response of physical systems to have a portrayal of digital representation. Complex systems such as heliostat fields for sustainable energy are good candidates for developing digital twins since the physical operation of facilities of this type can be highly time-consuming and weather-dependent. Therefore, a digital twin model of heliostat fields represents an adequate choice for the performance validation of new pointing correction algorithms with shorter assessing times. In this sense, one of the most important issues in the operation of heliostat fields for sustainable energy is to achieve a good accuracy of heliostats pointing to the target, even under physical errors of the solar field components and disturbances produced by external agents. However, since these types of disturbances have nonlinear characteristics, they should be dealt with by using nonlinear methods. This article presents a novel pointing correction technique based on nonlinear Limit Cycle Oscillators (LCOs) applied to the digital twin of a heliostat field. Analytical analysis, numerical verification, and further validation results are used to demonstrate the performance of the developed novel dynamic method.

Simulations of optical and dielectric properties of plasmonic Ag–LiNbO[formula omitted] metamaterial: Analysis of the geometrical parameters

We report the optical absorption of a multilayer system and the electrical properties of silver (Ag) naoparticles (NPs) embedded on LiNbO3 that acts as active layer. The multilayer system is constituted by Indium Tin Oxide (ITO), a square lattice of Ag NPs on the uniaxial crystal LiNbO3, the polymer PMMA and a substrate of SiO2. The effective dielectric function of the ensemble aggregates of Ag NPs and uniaxial LiNbO3 crystal are treated through the extended Maxwell–Garnett approximation. The multilayer absorbance for s- and p-polarization at normal and oblique incidences is determined by means of the Transfer Matrix Method. We demonstrate that an adequate choice of structural parameters such as NPs sizes, interparticle distances and layers thicknesses can produce an enhancement of optical absorption in the multilayer system. For filling factor higher, the system absorbance is greater. The Brewster angle is seen to be sensitive to the Ag NPs size, as far as the wavelength is varied. In addition, we evaluate the dielectric modulus parameter and the ac–electrical conductivity of the effective medium layer (active layer) in the perpendicular and parallel directions of the Ag NPs plane. For both directions, at f sufficiently high, we find the negative epsilon condition, typical characteristic observed in metamaterials. For the ac–electrical conductivity, we identify different resonances for the perpendicular and parallel directions. A bigger concentration of Ag NPs induces a higher intensity of ac–conductivity.

On the information content of explainable artificial intelligence for quantitative approaches in finance

AbstractWe simulate economic data to apply state-of-the-art machine learning algorithms and analyze the economic precision of competing concepts for model agnostic explainable artificial intelligence (XAI) techniques. Also, we assess empirical data and provide a discussion of the competing approaches in comparison with econometric benchmarks, when the data-generating process is unknown. The simulation assessment provides evidence that the applied XAI techniques provide similar economic information on relevant determinants when the data generating process is linear. We find that the adequate choice of XAI technique is crucial when the data generating process is unknown. In comparison to econometric benchmark models, the application of boosted regression trees in combination with Shapley values combines both a superior fit to the data and innovative interpretable insights into non-linear impact factors. Therefore it describes a promising alternative to the econometric benchmark approach.

Towards Enhanced Tunability of Aqueous Biphasic Systems: Furthering the Grasp of Fluorinated Ionic Liquids in the Purification of Proteins.

This work unfolds functionalized ABSs composed of FILs ([C2C1Im][C4F9SO3] and [N1112(OH)][C4F9SO3]), mere fluoro-containing ILs ([C2C1Im][CF3SO3] and [C4C1Im][CF3SO3]), known globular protein stabilizers (sucrose and [N1112(OH)][C4F9SO3]), low-molecular-weight carbohydrate (glucose), and even high-charge density salt (K3PO4). The ternary phase diagrams were determined, stressing that FILs highly increased the ability for ABS formation. The functionalized ABSs (FILs vs. mere fluoro-containing ILs) were used to extract lysozyme (Lys). The ABSs' biphasic regions were screened in terms of protein biocompatibility, analyzing the impact of ABS phase-forming components in Lys by UV-VIS spectrophotometry, CD spectroscopy, fluorescence spectroscopy, DSC, and enzyme assay. Lys partition behavior was characterized in terms of extraction efficiency (% EE). The structure, stability, and function of Lys were maintained or improved throughout the extraction step, as evaluated by CD spectroscopy, DSC, enzyme assay, and SDS-PAGE. Overall, FIL-based ABSs are more versatile and amenable to being tuned by the adequate choice of the phase-forming components and selecting the enriched phase. Binding studies between Lys and ABS phase-forming components were attained by MST, demonstrating the strong interaction between Lys and FILs aggregates. Two of the FIL-based ABSs (30 %wt [C2C1Im][C4F9SO3] + 2 %wt K3PO4 and 30 %wt [C2C1Im][C4F9SO3] + 25 %wt sucrose) allowed the simultaneous purification of Lys and BSA in a single ABS extraction step with high yield (extraction efficiency up to 100%) for both proteins. The purity of both recovered proteins was validated by SDS-PAGE analysis. Even with a high-charge density salt, the FIL-based ABSs developed in this work seem more amenable to be tuned. Lys and BSA were purified through selective partition to opposite phases in a single FIL-based ABS extraction step. FIL-based ABSs are proposed as an improved extraction step for proteins, based on their biocompatibility, customizable properties, and selectivity.

Fiber Laser Cutting Technology: Pilot Case Study in Mild Steel Cutting

Upon different traditional and unconventional contour cutting technologies, fiber laser cutting technology is increasingly emerging as the most adequate choice for modern industrial production. In this paper the basics, specific characteristics and associated benefits and opportunities, as well as latest research and development directions in fiber laser cutting technology were discussed. In addition, the study presents results obtained by realization of two pilot experiments, based on the use of one factor at a time (OFAT) experimental strategy, in fiber laser cutting of mild steel. The first OFAT experiment considered the analysis and modelling of the effect of focus position on the kerf width and surface roughness, while the second OFAT experiment investigated the effect of the cutting speed. Based on the analysis of experimental results more adequate parameter settings than initial were identified which was one of the underlying motives and goals of the present study.

Immediate versus early loading of immediately placed bone-level tapered dental implants with hydrophilic surface in full arch maxillary rehabilitation: A pilot randomized clinical trial with 2-year follow-up.

This study aimed to compare implant stabilities between the immediate and early loaded, immediately placed bone-level tapered dental implants in the maxilla and to evaluate marginal bone loss (MBL), oral health-related quality of life (OHRQoL), and patient satisfaction at a 2-year follow-up. A pilot, prospective, randomized, controlled clinical trial was conducted on 24 maxillary failing dentition patients. The bone-level tapered implants of 12 patients were immediately loaded with temporary restorations, while the other 12 patients did not receive any kind of temporization. Implant-supported screw-retained complete porcelain-fused-to-metal prostheses were delivered to all patients in the seventh postoperative week. The insertion torque values of implants assigned to the immediate and early loading groups were 33.0 ± 4.87 and 29.26 ± 8.31 Ncm, respectively. The dynamics of implant stability changes from implant placement up to a 2-year follow-up were similar for both groups (Penguin®, p = 0.268; Ostell®, p = 0.552), while the MBL was at submillimeter level. The cumulative implant survival rate was 91.80% for immediately loaded implants and 97.22% for early loaded implants, without significant difference (p = 0.162). The total score on the Oral Health Impact Profile questionnaire significantly decreased over time in both groups, indicating improvement in OHRQoL (p < 0.001), and the high level of patient satisfaction remained after 2 years of function regardless of a loading protocol. Both loading protocols, immediate and early, of six immediately placed bone-level tapered dental implants are an adequate treatment choice for fixed rehabilitation of the maxillary failing dentition.

The Factors of the Distribution of Grammatical Categories and Phenomena in Contemporary Czech

As to the application of the grammar within communication, we distinguish between two contingencies: a) grammatical categories which attach to the objective reality (verbal tenses, number, gender etc.), b) those which do not (in Czech for example the category of case). The relation between grammar and objective reality is not naturally rectilinear and troublefree. It could be complicated by various factors - not only the different type of language but also actualization which we comprehend as the unusual application of a grammatical form (often in order to gain more expressive term) - for example the sentence in the future tense Budeš psát (You will write) functions as that in the stressed imperative mood. To speakers with the advanced knowledge of Czech it is possible to present also special unmarked grammatical categories where a respective grammatical form can have more than one meaning. In the sentence Studuje český a německý jazyk (He studies Czech and German languages) the word jazyk (language) has the form of singular but the meaning of plural. There are many factors which influence the adequate choice of a grammatical category. In this respect the semantics are applied to a large extend and in various ways. The important role can be also played by number and so-called signal words which need the usage of a concrete morphological category (for example after the adverb včera (yesterday) must the preterite tense follow). From the linguo-didactic point of view this theme is very important and it is necessary to go on working it out.

Improved Real‐Time Post‐Processing for Quantum Random Number Generators

AbstractRandomness extraction is a key problem in cryptography and theoretical computer science. With the recent rapid development of quantum cryptography, quantum‐proof randomness extraction has also been widely studied, addressing the security issues in the presence of a quantum adversary. In contrast with conventional quantum‐proof randomness extractors characterizing the input raw data as min‐entropy sources, it is found that the input raw data generated by a large class of trusted‐device quantum random number generators can be characterized as the so‐called reverse block source. This fact enables us to design improved extractors. Two novel quantum‐proof randomness extractors for reverse block sources that realize real‐time block‐wise extraction are proposed specifically. In comparison with the general min‐entropy randomness extractors, the designs achieve a significantly higher extraction speed and a longer output data length with the same seed length. In addition, they enjoy the property of online algorithms, which process the raw data on the fly without waiting for the entire input raw data to be available. These features make the design an adequate choice for the real‐time post‐processing of practical quantum random number generators. Applying the extractors to the raw data generated by a widely used quantum random number generator, a simulated extraction speed as high as 300 Gbps is achieved.

Reconstruction of midface defects after surgical treatment of skull base tumors

Aim. To perform a retrospective analysis of the results of surgical treatment of patients with anatomically widespread malignant skull base tumors and evaluate the possibility of using various types of closure of skull base defects. Materials and methods. The study is based on a retrospective analysis of medical records of 139 patients with midface tumors aged 14 to 77 years, operated from 1995 to 2023. Histological structure of the tumors was different. we divided all methods of reconstruction of midface defects into two groups. In the group 1, plastic closure of the defect was per-formed using flaps from anatomical areas located close to the defect. In the group 2, reconstruction was performed using flaps from distant anatomical areas. Results. In the postoperative period, we did not observe gross cicatricial face deformities, impaired chewing and swallowing functions due to cicatricial contractures of chewing muscles. Titanium mesh for reconstruction was used in 68 (48.9 %) cases. The osteoperiosteal aponeurotic flap was used in 5 cases, of which in 3 (3.8 % of the total number of patients of the 1st group) – in combination with the temporal muscle. The thoracodorsal flap was used in 62 (44.6 %) patients. various methods of its movement and combination with the anterior dentate muscle were used. In 41 (66.1 %) cases, good cosmetic and functional results were obtained. These indicators correlated with adequate choice of reconstruction method allowing elimination of most of the impaired functions. Conclusion. The use of the presented technologies for plastic closure of post-resection defects of various parts of the skull base, including those combined with extensive damage to the midface, leads to leveling of the cosmetic and functional consequences of surgical aggression.

Optimal run-and-tumble in slit-like confinement

Run-and-tumble is a basic model of persistent motion and a motility strategy widespread in micro-organisms and individual cells. In many natural settings, movement occurs in the presence of confinement. While accumulation at the surface has been extensively studied, the transport parallel to the boundary has received less attention. We consider a run-and-tumble particle confined inside a slit, where motion in the bulk alternates with intermittent sojourns at the wall. We first propose a discrete-direction model that is fully tractable and obtain the exact diffusion coefficient characterizing the long-time exploration of the slit. We then use numerical simulations to show that with an adequate choice of parameters, our analytical prediction provides a useful approximation for the diffusion coefficient of run-and-tumble with continuous direction. Finally, we identify the conditions that maximize diffusion within the slit and discuss the optimal mean run time. For swimming bacteria, we find that the optimum is typically reached when the mean run length is comparable to the confinement size. Published by the American Physical Society 2024

Failed spinal anesthesia for cesarean delivery: prevention, identification and management.

There is an increasing awareness of the significance of intraoperative pain during cesarean delivery. Failure of spinal anesthesia for cesarean delivery can occur preoperatively or intraoperatively. Testing of the neuraxial block can identify preoperative failure. Recognition of the risk of high neuraxial block in repeat spinal in case of preoperative failure is important. Knowledge of risk factors for block failure facilitates prevention by selecting the most appropriate neuraxial procedure, adequate intrathecal doses and choice of technique. Intraoperative pain is not uncommon, and neither obstetricians nor anesthesiologists can adequately identify intraoperative pain. Early intraoperative pain should be treated differently from pain towards the end of surgery. Block testing is crucial to identify preoperative failure of spinal anesthesia. Repeat neuraxial is possible but care must be taken with dosing. In this situation, switching to a combined spinal epidural or an epidural technique can be useful. Intraoperative pain must be acknowledged and adequately treated, including offering general anesthesia. Preoperative informed consent should include block failure and its management.

Classifying Maxillary Sinuses of Polish Patients for Sinus Lift: A Pilot Study.

To date, there is no systematic anatomical classification available that could help clinicians in choosing between the lateral and palatal approach in sinus lift procedures. The aim was to provide a simple-to-use and memorable classification of the maxillary sinus concerning the thickness of lateral and palatal walls to facilitate the most adequate choice for the window location during direct sinus floor elevation. Cone beam computed tomography scans were consecutively obtained for 200 maxillary sinuses of patients needing dental implant placement with potential maxillary sinus augmentation. The thickness and height of the alveolar bone of the lateral and palatal walls of the maxillary sinuses were assessed. Four variants were distinguished. Class 0: an adequate sub-sinus residual bone height; without the need for sinus floor augmentation. Classes 1-3 had a reduced sub-sinus residual bone height. Class 1: a thinner lateral than palatal sinus wall. Class 2 (the most frequent; 49%): the comparable thickness of both walls in which either lateral, palatal, or crestal window osteotomies can be applied. Class 3 (the least frequent; 3%): a thinner palatal sinus wall in comparison to the lateral wall. The presented anatomical classification simplifies the decision-making process of choosing the most adequate window location and osteotomy technique.